Move isFileExist method to IO thread.

[MohitMaliFtechiz]

See parent issue #4035

Describe the bug
We are using the isFileExist method to check whether the file exists or not, but we are using the runBlocking which uses the mainThred and due to this we are facing an Input dispatching timed out error. The playStore reported this error, and in the last 60 days, there are 2 errors reported by the playStore.

Expected behavior
We should perform this action on the IO thread so that we will not face this type of issue.

Logs

at jdk.internal.misc.Unsafe.park (Native method)
  at java.util.concurrent.locks.LockSupport.parkNanos (LockSupport.java:252)
  at kotlinx.coroutines.BlockingCoroutine.joinBlocking (BlockingCoroutine.java:88)
  at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking (BuildersKt__Builders.kt:59)
  at kotlinx.coroutines.BuildersKt.runBlocking (Builders.kt:1)
  at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default (BuildersKt__Builders.kt:38)
  at kotlinx.coroutines.BuildersKt.runBlocking$default (Builders.kt:1)
  at org.kiwix.kiwixmobile.core.extensions.FileExtensionsKt.isFileExist (FileExtensions.kt:26)
  at org.kiwix.kiwixmobile.core.settings.StorageCalculator.availableBytes (StorageCalculator.java:40)
  at org.kiwix.kiwixmobile.core.settings.StorageCalculator.availableBytes$default (StorageCalculator.java:39)
  at org.kiwix.kiwixmobile.zimManager.libraryView.AvailableSpaceCalculator.hasAvailableSpaceForBook (AvailableSpaceCalculator.java:58)
  at org.kiwix.kiwixmobile.zimManager.libraryView.adapter.LibraryViewHolder$LibraryBookViewHolder.bind (LibraryViewHolder.kt:63)
  at org.kiwix.kiwixmobile.zimManager.libraryView.adapter.LibraryViewHolder$LibraryBookViewHolder.bind (LibraryViewHolder.kt:46)
  at org.kiwix.kiwixmobile.core.base.adapter.AbsDelegateAdapter$DefaultImpls.bind (AbsDelegateAdapter.kt:35)
  at org.kiwix.kiwixmobile.zimManager.libraryView.adapter.LibraryDelegate.bind (LibraryDelegate.kt:35)
  at org.kiwix.kiwixmobile.zimManager.libraryView.adapter.LibraryDelegate.bind (LibraryDelegate.kt:35)
  at org.kiwix.kiwixmobile.core.base.adapter.AdapterDelegateManager.onBindViewHolder (AdapterDelegateManager.java:40)
  at org.kiwix.kiwixmobile.core.base.adapter.BaseDelegateAdapter.onBindViewHolder (BaseDelegateAdapter.kt:57)
  at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder (RecyclerView.java:7065)
  at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder (RecyclerView.java:7107)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline (RecyclerView.java:6012)
  at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline (RecyclerView.java:6279)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition (RecyclerView.java:6118)
  at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition (RecyclerView.java:6114)
  at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next (LinearLayoutManager.java:2303)
  at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk (LinearLayoutManager.java:1627)
  at androidx.recyclerview.widget.LinearLayoutManager.fill (LinearLayoutManager.java:1587)
  at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren (LinearLayoutManager.java:665)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2 (RecyclerView.java:4134)
  at androidx.recyclerview.widget.RecyclerView.dispatchLayout (RecyclerView.java:3851)
  at androidx.recyclerview.widget.RecyclerView.onLayout (RecyclerView.java:4404)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at androidx.swiperefreshlayout.widget.SwipeRefreshLayout.onLayout (SwipeRefreshLayout.java:689)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild (HeaderScrollingViewBehavior.java:149)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild (ViewOffsetBehavior.java:43)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout (CoordinatorLayout.java:918)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at androidx.constraintlayout.widget.ConstraintLayout.onLayout (ConstraintLayout.java:1873)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.layoutChild (CoordinatorLayout.java:1213)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayoutChild (CoordinatorLayout.java:899)
  at com.google.android.material.appbar.ViewOffsetBehavior.layoutChild (ViewOffsetBehavior.java:66)
  at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild (HeaderScrollingViewBehavior.java:153)
  at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild (ViewOffsetBehavior.java:43)
  at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout (CoordinatorLayout.java:918)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at androidx.drawerlayout.widget.DrawerLayout.onLayout (DrawerLayout.java:1263)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.LinearLayout.setChildFrame (LinearLayout.java:1829)
  at android.widget.LinearLayout.layoutVertical (LinearLayout.java:1673)
  at android.widget.LinearLayout.onLayout (LinearLayout.java:1582)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.widget.FrameLayout.layoutChildren (FrameLayout.java:332)
  at android.widget.FrameLayout.onLayout (FrameLayout.java:270)
  at com.android.internal.policy.DecorView.onLayout (DecorView.java:1442)
  at android.view.View.layout (View.java:25087)
  at android.view.ViewGroup.layout (ViewGroup.java:6835)
  at android.view.ViewRootImpl.performLayout (ViewRootImpl.java:4962)