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/main/java/com/keylesspalace/tusky/receiver/SendStatusBroadcastReceiver.kt

@@ -29,6 +29,7 @@ import com.keylesspalace.tusky.db.AccountManager
 import com.keylesspalace.tusky.entity.Status
 import com.keylesspalace.tusky.service.SendStatusService
 import com.keylesspalace.tusky.service.StatusToSend
+import com.keylesspalace.tusky.util.getSerializableExtraCompat
 import com.keylesspalace.tusky.util.randomAlphanumericString
 import dagger.android.AndroidInjection
 import javax.inject.Inject
@@ -54,9 +55,8 @@ class SendStatusBroadcastReceiver : BroadcastReceiver() {
                 NotificationHelper.KEY_SENDER_ACCOUNT_FULL_NAME
             )
             val citedStatusId = intent.getStringExtra(NotificationHelper.KEY_CITED_STATUS_ID)
-            val visibility = intent.getSerializableExtra(
-                NotificationHelper.KEY_VISIBILITY
-            ) as Status.Visibility
+            val visibility =
+                intent.getSerializableExtraCompat<Status.Visibility>(NotificationHelper.KEY_VISIBILITY)!!
             val spoiler = intent.getStringExtra(NotificationHelper.KEY_SPOILER).orEmpty()
             val mentions = intent.getStringArrayExtra(NotificationHelper.KEY_MENTIONS).orEmpty()