Remove the usage of deprecated methods

[nikhildahake]

This pull request reduces the number of deprecated method warnings from 66 to 3.

Here is a summary of the changes:

1. Replace AsyncTask.
2. Replace MockitoAnnotations.initMocks().
3. Add a separate class(TransmissionRemotePreferenceManager) to manage application preferences.
4. Replace getAdapterPosition() with getBindingAdapterPosition().
5. Use getSupportFragmentManager() instead of getFragmentManager().
6. Update deprecated method params.
7. Remove the usage of setHasOptionsMenu().
8. Remove the usage of startActivityForResult(). Use ActivityResultLauncher instead.
9. Update onAttach() to use Context instead of Activity.
10. Unable to run tests on emulator. So, changed useUnifiedTestPlatform => false
11. Update calls to deprecated methods with their updated versions. eg:
    a) context.getResources.getColor(R.color.alternative_accent) -> context.getResources.getColor(R.color.alternative_accent, null)
12. Update deprecated imports.

Video: https://www.loom.com/share/e084450a7e3c45eb8f0796c9b93b0f70?sid=2d8d61bd-c5e8-4d43-a668-e2206d5e872c