Core / DolphinQt / InputCommon: reduce the number disk writes when using DynamicInputTextures

to eliminate redundant unused members in Wii Remote extension objects.

After reading the previous commit, you might think "hold on, what's the
difference between GetProfileName and GetProfileDirectoryName"? These
two are being used for the exact same thing - figuring out where
profiles are stored - yet they return different values for certain
controllers like GC keyboards! As far as I can tell, the existing code
has been broken for GC keyboards since they were introduced a decade
ago. The GUI (and more recently, also InputCycler) would write and read
profiles in one location, and our code for loading profiles specified in
a game INI file would read profiles in another location.

This commit gets rid of the set of values used by the game INI code in
favor of the other set. This does breaking existing setups where a
GCKey profile has been configured in a game INI, but I think the number
of working such setups is vanishingly small. The alternative would make
existing GCKey profiles go missing from the profile dropdown in the GUI,
which I think would be more disruptive. The alternative would also force
new GCKey profiles into the same directory as GCPad profiles.

This commit also fixes a regression from d6c0f8e749. The Android GUI was
using GetProfileName to figure out what key to use in the game INI,
which made it use incorrect game INI entries for GameCube controller
profiles but not Wii Remote profiles. Now the Android GUI uses
GetProfileKey for this, fixing the problem.

For all your PSO needs.

To avoid duplicating information between Kotlin and C++.

Gets this out of the global namespace and into the Common namespace

Up until now, there have been two settings on Android that stored the
selected Wii Remote extension: the normal one that's also used on PC,
and a SharedPreferences one that's used by the overlay controls to
determine what controls to show. It is possible for these two to end up
out of sync, and my input changes have made that more likely to happen.

To fix this, let's rework how the overlay controller setting works.
We don't want it to encode the currently selected Wii Remote extension.
However, we can't simply get rid of the setting, because for some Wii
games we need the ability to switch between a GameCube controller and a
Wii Remote. What this commit does is give the user the option to select
any of the 4 GameCube controllers and any of the 4 Wii Remotes. (Before,
controllers 2-4 weren't available in the overlay.) Could be useful for
things like the Psycho Mantis fight in Metal Gear Solid. I'm also
switching from SharedPreferences to Dolphin.ini while I'm at it.

Co-authored-by: Charles Lombardo <clombardo169@gmail.com>