Add new migrations format

[manuelwedler]

See #2123 and verifier-alliance/database-specs#31

Changes:

• Adds dbmate as the migration tool as we also will have it in VerA
• Adds npm scripts to run dbmate to set it up depending on the command (we need to merge the two migration folders of sourcify and vera)
• Adds documentation about how to make new schema changes
• Removes db-migrate
• Adds a CI workflow to validate that the migrations work as expected

[marcocastignoli]

A couple questions while I continue reviewing

[marcocastignoli]

Seems like ln -r is not supported on mac

> rm -rf migrations-temp && mkdir -p migrations-temp && ln -srf ./database-specs/migrations/* ./migrations-temp/ && ln -srf ./migrations/* ./migrations-temp/

ln: illegal option -- r
usage: ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file [target_file]
       ln [-s [-F] | -L | -P] [-f | -i] [-hnv] source_file ... target_dir
       link source_file target_file
npm error Lifecycle script `migrate:setup` failed with error:

[manuelwedler]

Seems like ln -r is not supported on mac

Oh no, that's an issue...

[manuelwedler]

Seems like ln -r is not supported on mac

added the fix

[marcocastignoli]

LGTM! Great, I like how migrations are structured now! :)