Fix a few FFI leaks (#405)

Fix a few FFI leaks

These are instances where we obtain an FFIObject and don't call
Close on it to release the underlying reference on the Rust side.

The worst instance here was leaking an object per room member
every time we refreshed the member list

features/invitelist/impl/src/main/kotlin/io/element/android/features/invitelist/impl/InviteListPresenter.kt

@@ -131,14 +131,18 @@ class InviteListPresenter @Inject constructor(
 
     private fun CoroutineScope.acceptInvite(roomId: RoomId, acceptedAction: MutableState<Async<RoomId>>) = launch {
         suspend {
-            client.getRoom(roomId)?.acceptInvitation()?.getOrThrow()
+            client.getRoom(roomId)?.use {
+                it.acceptInvitation().getOrThrow()
+            }
             roomId
         }.execute(acceptedAction)
     }
 
     private fun CoroutineScope.declineInvite(roomId: RoomId, declinedAction: MutableState<Async<Unit>>) = launch {
         suspend {
-            client.getRoom(roomId)?.rejectInvitation()?.getOrThrow() ?: Unit
+            client.getRoom(roomId)?.use {
+                it.rejectInvitation().getOrThrow()
+            } ?: Unit
         }.execute(declinedAction)
     }