Re-create android icons, add a monochrome icon

Closes #558

android/app/src/main/AndroidManifest.xml

@@ -13,7 +13,8 @@
     <application
         android:label="Lichess"
         android:name="${applicationName}"
-        android:icon="@mipmap/ic_launcher">
+        android:icon="@mipmap/ic_launcher"
+        android:roundIcon="@mipmap/ic_launcher_round">
 
     <meta-data
       android:name="com.google.firebase.messaging.default_notification_icon"

android/app/src/main/res/drawable/ic_launcher_foreground.xml

@@ -0,0 +1,17 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="50"
+    android:viewportHeight="50">
+  <group android:scaleX="0.4888889"
+      android:scaleY="0.4888889"
+      android:translateX="12.777778"
+      android:translateY="12.777778">
+    <path
+        android:strokeWidth="1"
+        android:pathData="M38.956,0.5c-3.53,0.418 -6.452,0.902 -9.286,2.984C5.534,1.786 -0.692,18.533 0.68,29.364 3.493,50.214 31.918,55.785 41.329,41.7c-7.444,7.696 -19.276,8.752 -28.323,3.084C3.959,39.116 -0.506,27.392 4.683,17.567 9.873,7.742 18.996,4.535 29.03,6.405c2.43,-1.418 5.225,-3.22 7.655,-3.187l-1.694,4.86 12.752,21.37c-0.439,5.654 -5.459,6.112 -5.459,6.112 -0.574,-1.47 -1.634,-2.942 -4.842,-6.036 -3.207,-3.094 -17.465,-10.177 -15.788,-16.207 -2.001,6.967 10.311,14.152 14.04,17.663 3.73,3.51 5.426,6.04 5.795,6.756 0,0 9.392,-2.504 7.838,-8.927L37.4,7.171z"
+        android:strokeLineJoin="round"
+        android:fillColor="#ffffff"
+        android:strokeColor="#ffffff"/>
+  </group>
+</vector>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-  <background android:drawable="@mipmap/ic_launcher_background"/>
-  <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
-</adaptive-icon>
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+    <monochrome android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

android/app/src/main/res/values/ic_launcher_background.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#131416</color>
+</resources>