VideoBackends / VideoCommon: add type enum to dictate how the texture is used; support texture 2d

[iwubcode]

Dolphin leverages a (2D) texture array for all its GC/Wii native textures. However, to support more interesting graphical features, I expanded to add cube map (#12061 ) support. This worked but was done as a texture flag. Now I want to add support for a standard 2d texture. Having it as a flag is odd, so I introduced a new type enumeration that dictates what the texture format is. At the moment, the possibilities are 2d texture array, 2d texture, or cube map. In the future (if needed) this could be expanded to 3d textures, cube map arrays, etc as well.

This also adds support for 2d textures from a texture perspective (samplers need more work)

EDIT: Thank you @TellowKrinkle for the help on the Metal backend.

[TellowKrinkle]

Looked over the code but didn't test it

[dolphin-ci]

FifoCI detected that this change impacts graphical rendering. Here are the behavior differences detected by the system:

• fishing-resort-map on mtl-osx-m1: failed to render
• metroid-visor on mtl-osx-m1: diff
• mp7-text on mtl-osx-m1: failed to render
• tla-menu on mtl-osx-m1: diff

_{^{automated-fifoci-reporter}}