mute: migrating muted_threads to new mute list

This patch depends on: Adding ability to mute hashtag from SearchView

This is the last patch for the new mute list feature

- Removing MutedThreadsManager
- Adding system to migrate existing muted threads to new mute list

Closes: https://github.com/damus-io/damus/issues/1718
Closes: https://github.com/damus-io/damus/issues/856
Lighting Address: fishcharlie@strike.me
Signed-off-by: Charlie Fish <contact@charlie.fish>
Reviewed-by: William Casarin <jb55@jb55.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/ContentView.swift

@@ -674,7 +674,6 @@ struct ContentView: View {
                                       postbox: PostBox(pool: pool),
                                       bootstrap_relays: bootstrap_relays,
                                       replies: ReplyCounter(our_pubkey: pubkey),
-                                      muted_threads: MutedThreadsManager(keypair: keypair),
                                       wallet: WalletModel(settings: settings),
                                       nav: self.navigationCoordinator,
                                       music: MusicController(onChange: music_changed),