Multiple fixes to the conversation selector for projects
Multiple fixes to the conversation selector for projects

- Conversations are not ordered as in the app navigation
- Conversation icons are not as "expected"
- Adjust selection style to current state of the art
- Better styling of the headline

Signed-off-by: Joas Schilling <ab43a7c9cb5b2380afc4ddf8b3e2583169b39a02@schilljs.com>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed