Was using the wrong key previously

Since you can manually change the config file now, users can force the material you theme under Android 12 and that will result in crashing on startup. This swaps to the default theme if that happens.

It would break reading floating point settings

Previously this could cause problems if a version of the template generated for WriteSetting didn't use the type you needed (e.g. floating point values). Now these are all ready without having to be used within frontend_common first.

On compliant Wayland compositors windows are matched to their .desktop files by comparing the appId window property to the name of the .desktop file without the .deskop extension.

Qt5/6 by default set this property to the basename of the binary (IE `yuzu`) which does not match the expected value `org.yuzu_emu.yuzu`. We can fix this and fix window associations on compliant compositors (like Plasma) by using the `setDesktopFileName()` function which will set the appId window property. This is a no-op on X11 so is safe to be ran without guards.

Hides fastmem toggle when CPU Debugging is disabled

Co-Authored-By: SachinVin <26602104+SachinVin@users.noreply.github.com>

Co-Authored-By: GPUCode <47210458+GPUCode@users.noreply.github.com>

Co-Authored-By: GPUCode <47210458+GPUCode@users.noreply.github.com>