chore: configure automatic screenshots

[AsCress]

Configures automatic screenshots in our pipelines.
Whenever a new release is made, new screenshots would automatically be captured in the release pipeline for upload to the Google PlayStore.

Changes

• ScreenshotsTest is added to capture screenshots using fastlane screengrab.
• Required permissions are added in the AndroidManifest, which include android.permission.DISABLE_KEYGUARD, android.permission.WAKE_LOCK, android.permission.CHANGE_CONFIGURATION and android.permission.DUMP.
• A new GitHub action (screenshot-android/action.yml) is added, which takes care of creating an emulator and capturing screenshots.
• The release pipeline release.yml is configured accordingly to push changes to the fastlane branch and then promote the existing APK to the production track.

Screenshots / Recordings

Here, is a screen recording of the test:

Screen_recording_20240726_161336.mp4

Checklist:

• No hard coding: I have used resources from strings.xml, dimens.xml and colors.xml without hard coding any value.
• No end of file edits: No modifications done at end of resource files strings.xml, dimens.xml or colors.xml.
• Code reformatting: I have reformatted code and fixed indentation in every file included in this pull request.
• No extra space: My code does not contain any extra lines or extra spaces than the ones that are necessary.

[github-actions]

Build successful. APKs to test: https://github.com/fossasia/pslab-android/actions/runs/10110176250/artifacts/1743506731