Render pass cleanup (implements #904)

[floooh]

• [x] change recipe blog post: https://floooh.github.io/2024/02/26/sokol-spring-cleaning-2024.html
• [x] remove contexts
• [x] rename sg_pass to sg_attachments, sg_make_pass() => sg_make_attachments() (and use
• [x] drive-by fix for #714: change GL_MAX_VERTEX_UNIFORM_VECTORS to GL_MAX_VERTEX_UNIFORM_COMPONENTS (a minor breaking change in sg_limits).
• [x] sg_pass for the all-in-one param going into the new unified sg_begin_pass()
  • [x] dummy backend
  • [x] gl backend
  • [x] metal backend
  • [x] d3d11 backend
  • [x] wgpu backend
• [x] new sg_pass struct with sg_pass_action and sg_attachments
• [x] change sg_begin_pass() to take const sg_pass*
• [x] new sg_swapchain struct which contains backend-specific swapchain surfaces (etc...)
• [x] integrate sg_swapchain into sg_begin_pass()
  • [x] dummy backend
  • [x] metal backend
  • [x] gl backend
  • [x] d3d11 backend
  • [x] wgpu backend
• [x] fix _sg_validate_begin_pass() to also check swapchain arguments (and make sure they are mutually exclusive with sg_attachments)
  • [x] metal backend
  • [x] gl backend
  • [x] d3d11 backend
  • [x] wgpu backend
• [x] remove sg_begin_default_pass()
• [x] remove swapchain attributes from sg_context_desc
• [x] _sg.cur_pass related cleanup
  • [x] metal
  • [x] d3d11
  • [x] gl
  • [x] wgpu
• [x] implement sapp_gl_get_framebuffer()
  • [x] macOS
  • [x] iOS
  • [x] Android
  • [x] Emscripten
  • [x] Windows
  • [x] Linux/GLX
  • [x] Linux/EGL
• [x] find a better name for sg_context_desc ( => sg_environment)
• [x] change semantics of pixel formats and sample count in sg_context_desc to mean "default pipeline attributes"
• [x] replace granular getter functions in sokol_app.h with sapp_swapchain sapp_get_swapchain(void) and this must fail when called outside the frame callback (to enforce correct usage)
• [x] Q: should the Metal swapchain description have the 'raw' surfaces instead of an MTLRenderPassDescriptor object? Would be more in line with the other platform, and less 'hardwired' to MTKView.
• [x] Metal: label the Metal render pass (also WGPU)
• [x] Metal: optionally support commandBuffer with retained references (via new config item sg_desc.mtl_use_command_buffer_with_retained_references, fixes https://github.com/floooh/sokol/issues/981)
• [x] D3D11: move swapchain MSAA resolve into sokol_gfx.h _sg_d3d11_end_pass() (like in the other backends)
• [x] fix related code-cleanup fixmes
• [x] fix tests
• [x] move backend.cur_pipeline up into generic state (maybe at a later time)
• [x] change sokolglue.h prefix to sglue, and remove the 'clever' included prepreocessor checks
• [x] make sokol_glue.h a regular bindings header(?)
• [x] fix sokol_gfx_imgui.h
• [x] fix sg_swapchain defaults to use the default values from sg_environment
• [x] fix all samples
  • [x] sapp
  • [x] metal
  • [x] d3d11
  • [x] glfw
    • [x] glfw+metal example
    • [x] multi-window example
    • [x] ...all other glfw examles
  • [x] html5
  • [x] wgpu
• [x] make swapchain depth buffer optional
  • [x] metal
  • [x] d3d11
  • [x] gl
  • [x] webgpu
• [x] allow defaults for color_format, depth_format and sample_count in sg_environment and sg_swapchain.
• [x] sokol_app.h: sapp_pixelformat, and allow to configure depth-buffer (none, depth-only, depth-stencil) move this into a later update
• [x] fix all bindings
  • [x] zig (https://github.com/floooh/sokol-zig/pull/57)
  • [x] odin (https://github.com/floooh/sokol-odin/pull/8)
  • [x] nim (https://github.com/floooh/sokol-nim/pull/28)
  • [x] rust (https://github.com/floooh/sokol-rust/pull/22)
• [x] fix dependent projects
  • [x] samples (https://github.com/floooh/sokol-samples/pull/137)
  • [x] pacman.c (https://github.com/floooh/pacman.c/pull/12)
  • [x] chips (https://github.com/floooh/chips-test/pull/33)
  • [x] v6502r (https://github.com/floooh/v6502r/pull/24)
  • [x] pacman.zig (https://github.com/floooh/pacman.zig/pull/23)
  • [x] kc85.zig (https://github.com/floooh/kc85.zig/pull/4)
  • [x] doom (https://github.com/floooh/doom-sokol/pull/1)
  • [x] cimgui-starter-kit (https://github.com/floooh/cimgui-sokol-starterkit/pull/18)
  • [x] qoiview (https://github.com/floooh/qoiview/pull/10)
• [x] fix sokol_app.h documentation
• [x] fix sokol_gfx_imgui.h documentation
• [x] fix sokol_gfx.h documentation
  • [x] sg_setup() + sokol_glue.h()
  • [x] sg_swapchain
  • [x] sg_environment
  • [x] sg_attachments
  • [x] sg_attachments_desc
  • [x] rewrite render passes section
• [x] test
  • [x] macOS + Metal
  • [x] macOS + GL
  • [x] iOS + Metal
  • [x] iOS + GL
  • [x] Android
  • [x] Windows + D3D11
  • [x] Windows + GL
  • [x] Web + WebGL2
  • [x] Web + WebGPU
• [x] update changelog
• [x] update readme
  • [x] merge sokol_gfx.h and sokol_app.h section and change the hello-triangle to use sokol_app.h

Merged:

• [x] sokol-zig
• [x] sokol-odin
• [x] sokol-nim
• [x] sokol-rust
• [x] sokol-samples
• [x] pacman.c
• [x] pacman.zig
• [x] kc85.zig
• [x] doom
• [x] cimgui-starter-kit
• [x] v6502r
• [x] chips-test
• [x] qoiview

[floooh]

Some time measurements for D3D11:

• 100k CreateRTV + CreateDSV + Release: 230ms
• 100k sg_begin_pass/sg_end_pass(): 133ms
• 100k CreateTexture2D + Release: 232ms

...these are just naively taking the time it takes to call those functions.

[kassane]

The issues on D binding persisted after this cleanup. :disappointed:

• https://github.com/kassane/sokol-d/issues/13

[floooh]

@kassane after this PR is merged I'll take care of a couple of other small PRs piling up since then and then I plan to look at the D bindings again.