WIP: Metal

[SamoZ256]

This is a work in progress Metal backend. TODOs:

• Viewport and scissor
• Regions when doing display transfer and texture copy
• Correct clipping
• Color mask
• Stencil ref
• Blend color
• Clear render targets after creation

[wheremyfoodat]

Hi!

I am not sure how feasible it is to upstream and maintain a Metal renderer on upstream at the moment, so I redirected the PR to a dedicated Metal branch instead of the upstream master branch for the time being.

Some notes:

• Please move metal-cpp into a submodule instead of including it in the repo, since that makes it a lot easier to update if needed and to search through the repo without getting hits on metal-cpp stuff
• Switch and replace of Handle -> HandleType has caused quite the mess in the core code. This is generally not a wanted change, both because random bits of text got changed and because Handle and similar names are used in all 3DS documentation/libraries/RE.
• If possible, please undo random older files being formatted/changed unnecessarily (eg all the service/kernel/memory files), those will be formatted eventually but doing it en masse and in unrelated PRs leads to the PR being impossible to review
  

[wheremyfoodat]

Nice work on the renderer of course, nice to see that particular scene running nicely on it.

Changing the PR to be a draft so it's not accidentally merged while it's not ready, feel free to change it back when you feel like it.

[wheremyfoodat]

Updated base branch to reflect the new renderer code upstream has, PR still merges gracefully thankfully.