wireguard: move enable checkbox to apply button and remove the general form

[fichtner]

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Is your feature request related to a problem? Please describe.

General tab is a bit low on value and just now with #6973 we have a nice way to ensure people find the "enable" checkbox by placing it with the apply button.

Describe the solution you like

In a nutshell remove the tab, maybe rename the Settings to Configuration to align with others (or add the individual tabs into the menu like we do with the firmware menu). Make sure the docs reflect the change but it shouldn't cause the amount of friction of earlier more fundamental reworks.

Describe alternatives you considered

Adding more options to the general settings tab but there aren't any that make sense. ;)

Additional context

Loosely related to #6973 as mentioned.

[fichtner]

One note from @swhite2 was the possibility of making the enable/apply pattern a reusable hook of some sort.

Also the services hook is not there. It's difficult anyway to display per instance. Just need to check status page and services page more or less align with the whole implementation.