The database settings could also be overridden in the configuration file
besides the command line.
We should therefore pass the path to the runtime configuration file, so
the Alembic process can initialize its configuration from the same file
and use the same settings.
If the path of the default database engine is overridden via `--workdir`
option then it won't be visible to the new `python` subprocess spawned
for Alembic.
Added Alembic environment and `run_db_migrations` logic to the entities
engine so database schema changes can be processed as soon as the
application is started.
Fabio Manganiello