Add option to choose which update channel to receive notifications for

[LostLuma]

Fixes #604 by allowing the user to choose between receiving all updates, betas and releases, or only releases (default).
This branch is based on the work from #679 and I will keep this as a draft until Max's work is merged into the upstream repo.

It'd however be awesome if these two PRs could land in the same release of ModMenu so I do not have to mark the new method in the UpdateInfo interface as being optional (and prob end up not being used a lot).

[LostLuma]

I just realized earlier that the update checking logic could be a bit smarter if the user can choose a channel, so this has been adjusted.

By making the user's preference for an update channel available to the update checker we can now handle a situation in which the user is on version 1.0.0 for a mod, and both version 1.0.1 and 1.1.0-beta.1 are available. If the preference is to only receive release versions the update checker can return version 1.0.1, otherwise it can return version 1.1.0-beta.1.

I don't think the Modrinth API supports selecting which version types one is looking for in the get latest versions from hashes route, so this can sadly not improve the update checking experience for mods not using a custom update checker. Maybe I'll look into contributing this to the Modrinth API in the future though since it seems very useful to me, also for other API consumers. Turns out the Modrinth API docs just don't include this info ...