Support MariaDB unix domain socket

Description I keep it brief: If you set PAPERLESS_DBHOST to a UDS, the "init-db-wait" service will _never_ complete, prohibiting the further start of the instance. I did not find _any_ workaround the "init-db-wait" service so currently I'm sadly stuck. The check performed by "init-db-wait" can be found [here]( --- The problem is that if you're using a UDS you mustn't set --host but --socket. --- I would suggest the following: 1. Provide an option to bypass initial checks (like waiting for Redis or MariaDB), but still execute migration and other _required_ startup jobs, preferably by an environment variable like USER_IS_NON_ROOT=1 for dropping privileges. 2. Check for a connection by using the Python MariaDB connector like in my reproduction. This would then include even PAPERLESS_DB_OPTIONS. Steps to reproduce 1. Ensure /run/mysqld/mysqld.sock points to a valid MariaDB/MySQL UDS 2. Set PAPERLESS_DBHOST=/run/mysqld/mysqld.sock 3. Co…