Fix various lint warnings (#4409)

- Remove empty file `ExampleInstrumentedTest.java`.
- Replace deprecated `MigrationTestHelper` constructor call.
- Add reified inline extension methods for `Bundle` and `Intent` to
retrieve `Parcelable` and `Serializable` objects by calling the core
`BundleCompat` and `IntentCompat` methods, to allow shorter syntax and
removing the need to pass the class explicitly.
- Replace deprecated `drawable.setColorFilter()` with simpler
`drawable.setTint()` (uses blend mode `SRC_IN` by default, has the same
effect as `SRC_ATOP` when the source is a color).
- Rename shadowed variables (mostly caught exceptions).
- Remove unnecessary `.orEmpty()` on non-null fields.
- Replace `.size() == 0` with `.isEmpty()`.
- Prevent `NullPointerException` when `account.getDisplayName()` is
`null` in `StatusBaseViewHolder.setDisplayName()`.
- Declare `customEmojis` argument as non-null in
`StatusBaseViewHolder.setDisplayName()` because it calls
`CustomEmojiHelper.emojify()` which now requires it to be non-null.
- Prevent `NullPointerException` when no matching filter is found in
`StatusBaseViewHolder.setupFilterPlaceholder()`.
- Remove deprecated call to `setTargetFragment()` (target fragment is
not used anyway).
- Remove deprecated call to `isUserVisibleHint()` and test if the view
has been destroyed instead.
- Remove some unused imports.
- Remove unnecessary casts.
- Rename arguments to supertype names when a warning is shown.
- Prevent a potential memory leak by clearing the
`toolbarVisibilityDisposable` reference in `onDestroyView()`.

app/src/androidTest/java/com/keylesspalace/tusky/MigrationsTest.kt

@@ -1,7 +1,6 @@
 package com.keylesspalace.tusky
 
 import androidx.room.testing.MigrationTestHelper
-import androidx.sqlite.db.framework.FrameworkSQLiteOpenHelperFactory
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.platform.app.InstrumentationRegistry
 import com.keylesspalace.tusky.db.AppDatabase
@@ -19,8 +18,7 @@ class MigrationsTest {
     @Rule
     var helper: MigrationTestHelper = MigrationTestHelper(
         InstrumentationRegistry.getInstrumentation(),
-        AppDatabase::class.java.canonicalName!!,
-        FrameworkSQLiteOpenHelperFactory()
+        AppDatabase::class.java
     )
 
     @Test