CommandBus: replace deprecated implementation.

Convert CommandBus from deprecated BroadcastChannel to a SharedFlow.

app/src/main/java/audio/funkwhale/ffa/FFA.kt

@@ -6,7 +6,6 @@ import androidx.appcompat.app.AppCompatDelegate
 import audio.funkwhale.ffa.koin.authModule
 import audio.funkwhale.ffa.koin.exoplayerModule
 import audio.funkwhale.ffa.utils.AppContext
-import audio.funkwhale.ffa.utils.Command
 import audio.funkwhale.ffa.utils.FFACache
 import audio.funkwhale.ffa.utils.Request
 import com.preference.PowerPreference
@@ -26,7 +25,6 @@ class FFA : Application() {
 
   var defaultExceptionHandler: Thread.UncaughtExceptionHandler? = null
 
-  val commandBus: BroadcastChannel<Command> = BroadcastChannel(10)
   val requestBus: BroadcastChannel<Request> = BroadcastChannel(10)
 
   override fun onCreate() {

app/src/main/java/audio/funkwhale/ffa/utils/Bus.kt

@@ -86,13 +86,15 @@ object EventBus {
 }
 
 object CommandBus {
+  private var _commands = MutableSharedFlow<Command>()
+  var commands = _commands.asSharedFlow()
   fun send(command: Command) {
     GlobalScope.launch(IO) {
-      FFA.get().commandBus.trySend(command).isSuccess
+    _commands.emit(command)
     }
   }
 
-  fun get() = FFA.get().commandBus.asFlow()
+  fun get() = commands
 }
 
 object RequestBus {