Toggle between Bridged and Routed modes

[Taikuh]

For more info on setting up a bridged access point, see here.

Since #379 is a bit old, and it's technically limited to a Bridged config option during installation, I'm opening this issue as a starting point. I am working on an easy way to toggle to Bridged Access Point configuration from raspap-webgui's default Routed Access Point configuration.

Ideally, there would eventually be a toggle on hostapd.php, with the irrelevant settings from Routed config disabled and greyed out so the end user won't try to change things they shouldn't.

I'm not well-versed with bash, php, and even just networking in general. Hopefully some others will be able to contribute!

[billz]

This PR has been merged. Many thanks @Taikuh!