Almost all the virtual functions in Renderer are part of dolphin's
"graphics api abstraction layer", which has slowly formed over the
last decade or two.
Most of the work was done previously with the introduction of the
various "AbstractX" classes, associated with texture cache cleanups
and implementation of newer graphics APIs (Direct3D 12, Vulkan, Metal).
We are simply taking the last step and yeeting these functions out
of Renderer.
This "AbstractGfx" class is now completely agnostic of any details
from the flipper/hollywood GPU we are emulating, though somewhat
specialized.
(Will not build, this commit only contains changes outside VideoBackends)
Texture cache occasionally mutates textures for efficiency.
Which is awkward if we want to borrow those textures from texture cache
to do something else, such as a graphics debugger, or async presentation
on another thread.
Content locking provides a way to signal that the contents of a texture
cache entry should not change. Texture cache will be forced to use
alternative strategies.
The whole ownership model was getting a bit of a mess, with a some
of special cases to deal with. And I'm planning to make it even more
complex in the future.
So here is some upfront work to convert it over to reference counted
pointers.
This was added in 385d8e2b15, but became somewhat redundant with Do in 4c7bbd96e4, and completely redundant now that std::is_trivially_copyable_v is well-supported.
The only remaining casts for these types that I know of are in TextureInfo (where format_name is set to the int version of the format, and since that affects filenames and probably would break resource packs, I'm not changing it) and in TextureDecoder_Common's TexDecoder_DrawOverlay, which will be handled separately.
