Add flag for custom path to .symfony.local.yaml

[cngJo]

I stumbled across this, because my playwright setup starts the symfony server:start from ./tests/playwright and not from ./ where my .symfony.local.yaml is located.

By looking in the help output, there seems to be no option currently, to modify the path to load .symfony.local.yaml from.
For now, it's solved by a simple symlink of the config file to ./tests/playwright.

I know the feature with the config file is currently experimental, but would you be open to a Pull Request, that adds a simple --config-file option? If so, I'd be happy to provide such a Pull Request 🙂

[fabpot]

That sounds reasonable to me.