Support UNIX socket connection for MySQL/MariaDB

[jacrasmussen]

To support unix socket connections to MySQL/MariaDB it's necessary to add an additional parameter (unix_socket) to the connection.

[fisharebest]

If you select localhost as the server, then the connection should use the unix socket automatically.

(But if you select 127.0.0.1, the the connection will use the mysql network protocol).

In your php.ini configuration file, the setting for pdo_mysql.default_socket must be set to the correct path.

[jacrasmussen]

I actually tried that among other suggestions, but I hadn't any luck connecting to the database until I reviewed the Laravel logic and found that the unix_socket parameter must be set.

I've prepared a change that I'm happy to share as a pull request, I've run the tests and setup locally and confirmed the change works and connects as expected against the socket.

[fisharebest]

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