* Allow for creation of indexes for PostgeSQL and SQLite
PostgreSQL and SQLite do not allow creation of general indexes within a `CREATE TABLE` statement, so a method is required to generate `CREATE INDEX` statements for these.
`create_table_from_entity` avoids creating invalid statements for non-MySQL backends,
forcing uses to explicitly run `create_index_from_entity`. Ideally creating indexes would be removed from `create_table_from_entity` entirely, but this would introduce a breaking change for MySQL use.
* Remove index creation from create_table_from_entity
Use `create_index_from_entity` for all index creation for consistency across all backends. This is a backwards incompatible change, affecting those using MySQL backend when creating the schema only.
* Revert change to join_8 test after migration to new indexes entity
