Add a CI check to make sure typeorm models are always in sync with migrations

[FelixMalfait]

When we update a model that lives in core/metadata schema we need to run the following command to generate the relevant migrations:

npx nx run twenty-server:typeorm --migration:generate src/database/typeorm/metadata/migrations/nameOfYourMigration -d src/database/typeorm/metadata/metadata.datasource.ts # (orcore data source)

Sometimes people will create migrations manually or just forget to run this command, resulting in migrations not being created at the right moment and usually getting picked up in a sub-sequent unrelated PR.

In order to avoid this, we would like to add a step in the server CI that will make sure the migration generation commands do not generate any file.