Replace telepathy-logger with a private Tracker database

This merge request is the continuation/update of prior work (https://gitlab.gnome.org/GNOME/polari/-/commits/wip/fmuellner/tracker, https://gitlab.gnome.org/GNOME/polari/-/commits/wip/carlosg/tracker) that I revisited the last couple of weekends, modernized and rebased on fresh main. Some highlights:

• Commit history is less of a mess, commits have been squashed and given some more sense of direction
• Tracker usage has been made modern, spot on and using minimal resources from the start
• Javascript code has been modernized, within my limitations
• Log migration has been integrated into the UI, now you just have to watch the progress bar finish, and scroll
• Remaining questions about ordering of messages received on the same second have been fixed

So feature wise I think this is mostly ready for review/merge. However there's maybe some open questions to make before we let this perform a migration in user systems:

• It might make sense to use irc: URIs to refer to channels and usernames to make the stored data most RDF-happy, this might be however not trivial to pull proper IRC uris from telepathy and the log importer helper object.
• Should we attempt some more metadata extraction from messages? These might be useful for extended search features in the future, things that are coming to mind are:
  • Link extraction
  • Nick mentions