Refactor code and clean up unused resources

- Replace `suspendCoroutine` with `suspendCancellableCoroutine` in helper classes for better cancellation support.
- Replace `bundleOf` with manual `Bundle` initialization in `MediaControllerExt` and `SettingsFragment`.
- Remove unused constants in `Keys.kt` and redundant `onTerminate` override in `Radio.kt`.
- Clean up syntax and remove semicolons in `MainActivity.kt`.

app/src/main/java/com/michatec/radio/Radio.kt

@@ -34,9 +34,4 @@ class Radio : Application() {
         AppThemeHelper.setTheme(PreferencesHelper.loadThemeSelection())
     }
 
-    /* Implements onTerminate */
-    override fun onTerminate() {
-        super.onTerminate()
-    }
-
 }