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>

damusTests/Mocking/MockDamusState.swift

@@ -44,7 +44,6 @@ func generate_test_damus_state(
                            postbox: .init(pool: pool),
                            bootstrap_relays: .init(),
                            replies: .init(our_pubkey: our_pubkey),
-                           muted_threads: .init(keypair: test_keypair),
                            wallet: .init(settings: settings),
                            nav: .init(),
                            music: .init(onChange: {_ in }),