25% of the screen isn't necessarily wide enough on phones,
especially not in portrait mode.

https://bugs.dolphin-emu.org/issues/12029

We currently have one way of opening the menu on touch screen
devices (swiping down from the top of the screen to bring up the
action bar and selecting the menu in the action bar), and another
way of opening the menu on Android TV (pressing Back). However,
some devices that claim to support touch (or don't support
leanback? Dolphin currently conflates the two) don't actually let
you swipe down from the top of the screen in the way that Dolphin
expects, notably Chromebooks. There are also some phones where you
can swipe down from the top of the screen but this for some reason
doesn't lead to the action bar becoming visible, though we are
getting less reports about this nowadays than in the past.

This change makes us use the Back method on all devices,
since it should work on all devices with no significant drawbacks.

Unfortunately, we not only have two different ways of triggering
the menu but actually two entirely different menus, with the
non-touch menu not implementing options that only are revelant
when using a touch screen. A later commit will add the missing
features to the menu that we now use on all devices.

The Activity is responsible for just its views and menus and such. It
signals the Fragment via setGamePath, StartEmulation and StopEmulation.

The Fragment manages the actual emulation lifecycle. It is solely
responsible for calling the NativeLibrary lifecycle methods.

With this lifecycle simplification, the NativeLibrary no longer needs to
kill the Activity. It happens normally now.

This simplifies a lot of things, live handling rotation.