Improve loading states

[malteish]

Some states of our web app are not very user-friendly. The loading states for example give little information, and sometimes even that is wrong. Here are 2 examples that should be improved upon:

when signing in

After signing the messages, the app says it is "Fetching contacts". In this state, it does lots of stuff in the background - and often some of that stuff fails. The state should be changed to:

1. be more informative. If lots of stuff is happening, tell the user some of it, preferrably the successful things.
2. have a timeout and a decent error handling. If something fails, tell the user, and give some guidance. Like this: "was unable to publish your profile. If this error persists, please file an issue [here](link to github)"

when adding a conversation (or opening a message that has been received from a new contact)

When adding a contact, a banner saying "this contact has not published their profile yet" is displayed. Instead, the banner should read "searching the profile" while the profile is being loaded.
Only if no profile can be found should the message update to "this contact has not published their profile yet".

Why? Sometimes the loading takes a while and the message on the banner is wrong whenever the profile is found a few seconds later.

[malteish]

vlc-record-2024-09-04-10h48m03s-no_profile_banner.mp4-.mp4

This video demonstrates the issue