feat: port diesel migrations to the new framework

[Mirko-von-Leipzig]

Migrates the sqlite migrations to the new framework introduced in #2093.

I also made some changes to the framework after dog fooding it here.

• CI runs diesel schema tests to ensure they match the migrations.
• active migrations now accepts raw SQL migrations in addition to rust ones
• migration codegen now expects a flat set of active migration files instead of folders
• migration codegen now expects files to have three digit prefix instead of just lexicographically sorting them
  • if we ever have more than 1000 migrations I think we have a problem, but we can always bump it to four digits..

[kkovaacs]

Looks good to me!

[sergerad]

LGTM but I don't follow why those 3 byte arrays are now nullable when other ones in the same schema aren't?

[Mirko-von-Leipzig]

LGTM but I don't follow why those 3 byte arrays are now nullable when other ones in the same schema aren't?

If you look at the original sqlite for it, they were actually nullable, but the diesel macros for them for whatever reason were altered to be non-null. So when we redid this manually, the more "correct" diesel was generated.

I'll fix the schema to match what we want.