fix: add Supabase configuration and initial database setup

[gentlementlegen]

Resolves #32

Moved the Supabase migrations from https://github.com/ubiquity/ubiquibot here because we are still using the DB and this is needed to do a local setup, or eventually to move the db to another instance. This is specially relevant because now Supabase limits to 2 active instances which makes local setup required for ease of use.

[gentlementlegen]

@rndquu Ideally all the plugins should use their own DB except for anything related to OAuth login since this one should be shared by everything. We can have a dedicated repository for this, otherwise that migration should indeed be moved here.

Having a separate repo seems cleaner because the Kernel does not reference supabase and doesn't need it to run, and that would avoid polluting the repo. I will create a repo.

[rndquu]

Ideally all the plugins should use their own DB

I've thought that we decided that all core plugins use a shared DB

[gentlementlegen]

@rndquu I feel like we had these discussions over and over again so at this point I am not even sure. Either way it will be simple for new devs / external orgs to have that repo on the side since it won't be required to set up the project, except for self host and local setup. Created https://github.com/ubiquity-os/database will push in a minute and close this PR.

[gentlementlegen]

Closed via the creation of a separate repository: https://github.com/ubiquity-os/database