Allow the user to specify a unix socket to connect to a database

[flawedworld]

GrapheneOS is currently using 'unix_socket' => '/run/mysqld/mysqld.sock' in production and it works fine, just that the config file needs to manually edited and the database wizard doesn't seem to expose this.

[SychO9]

I don't think we'd want more advanced fields on the wizard UI, I think being able to already specify the value through config.php is enough?

Closing for now, feel free to discuss further if necessary.

[askvortsov1]

I feel like the best course of action here is documenting the config.php support in https://docs.flarum.org/config, and possibly somewhere else? Agree that keeping the installation GUI minimal is probably best.

[SychO9]

Docs PR opened: flarum/docs#458