TWEAK: Layout/styling overhaul for the F1 menu

[aMannus]

What this PR does:

• Add helper functions for inserting padding above or below items and uses them to introduce padding around menu items.
• Adjust window padding in general
• Change sliders so they fit windows better
• Readjusted the locations of quite a few settings. For example, all D-pad related options that were under "Controller" before are now in their own flyout called "Controls" under "Enhancements".
• Consolidated "Audio", "Controller", "Graphics" and "Languages" under one menu called "Settings".
• Changed all checkboxes that open external windows to buttons, and added the ability to close the windows with the "X" button to windows that were missing it. As a part of this, newly opened windows will now be focused automatically.

I don't know how far along the ImGui cleanup in LUS is. I've asked about it a couple of times but I've not really gotten an answer so far, so I decided to push through with this PR and finish it anyway. I'd love for this to get in before the cleanup in ImGuilmpl.cpp is done, but I don't know if that's feasible or not.

https://cdn.discordapp.com/attachments/989182407213219840/1004449471691763812/2022-08-03_19-45-00.mp4

[aMannus]

Remade as #1026 because I couldn't fix the broken file permissions...