Follow breaking changes to get SchemaMigration DB table name on Rails 7.1+

[andretf]

Fixes error when click on "Edit Database" on Rails 7.1+.
This is the new way to get the SchemaMigration table name:

ActiveRecord::Base.connection.schema_migration.table_name

See more at: rails/rails#45908 and the final changelog at https://github.com/rails/rails/releases/tag/v7.1.0

Move ActiveRecord::InternalMetadata to an independent object.

ActiveRecord::InternalMetadata no longer inherits from ActiveRecord::Base and is now an independent object that should be instantiated with a connection. This class is private and should not be used by applications directly. If you want to interact with the schema migrations table, please access it on the connection directly, for example: ActiveRecord::Base.connection.schema_migration.

Eileen M. Uchitelle