Render pass cleanup (implements #904)

[floooh]

• change recipe blog post: https://floooh.github.io/2024/02/26/sokol-spring-cleaning-2024.html
• remove contexts
• rename sg_pass to sg_attachments, sg_make_pass() => sg_make_attachments() (and use
• drive-by fix for GL_MAX_VERTEX_UNIFORM_VECTORS is not included per default in GL3.3 #714: change GL_MAX_VERTEX_UNIFORM_VECTORS to GL_MAX_VERTEX_UNIFORM_COMPONENTS (a minor breaking change in sg_limits).
• sg_pass for the all-in-one param going into the new unified sg_begin_pass()
  • dummy backend
  • gl backend
  • metal backend
  • d3d11 backend
  • wgpu backend
• new sg_pass struct with sg_pass_action and sg_attachments
• change sg_begin_pass() to take const sg_pass*
• new sg_swapchain struct which contains backend-specific swapchain surfaces (etc...)
• integrate sg_swapchain into sg_begin_pass()
  • dummy backend
  • metal backend
  • gl backend
  • d3d11 backend
  • wgpu backend
• fix _sg_validate_begin_pass() to also check swapchain arguments (and make sure they are mutually exclusive with sg_attachments)
  • metal backend
  • gl backend
  • d3d11 backend
  • wgpu backend
• remove sg_begin_default_pass()
• remove swapchain attributes from sg_context_desc
• _sg.cur_pass related cleanup
  • metal
  • d3d11
  • gl
  • wgpu
• implement sapp_gl_get_framebuffer()
  • macOS
  • iOS
  • Android
  • Emscripten
  • Windows
  • Linux/GLX
  • Linux/EGL
• find a better name for sg_context_desc ( => sg_environment)
• change semantics of pixel formats and sample count in sg_context_desc to mean "default pipeline attributes"
• 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)
• 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.
• Metal: label the Metal render pass (also WGPU)
• Metal: optionally support commandBuffer with retained references (via new config item sg_desc.mtl_use_command_buffer_with_retained_references, fixes Use retained command buffer in sokol_gfx #981)
• D3D11: move swapchain MSAA resolve into sokol_gfx.h _sg_d3d11_end_pass() (like in the other backends)
• fix related code-cleanup fixmes
• fix tests
• move backend.cur_pipeline up into generic state (maybe at a later time)
• change sokol_glue.h prefix to sglue_, and remove the 'clever' included prepreocessor checks
• make sokol_glue.h a regular bindings header(?)
• fix sokol_gfx_imgui.h
• fix sg_swapchain defaults to use the default values from sg_environment
• fix all samples
  • sapp
  • metal
  • d3d11
  • glfw
    • glfw+metal example
    • multi-window example
    • ...all other glfw examles
  • html5
  • wgpu
• make swapchain depth buffer optional
  • metal
  • d3d11
  • gl
  • webgpu
• allow defaults for color_format, depth_format and sample_count in sg_environment and sg_swapchain.
• sokol_app.h: sapp_pixelformat, and allow to configure depth-buffer (none, depth-only, depth-stencil) move this into a later update
• fix all bindings
  • zig (Fixes for sokol-gfx pass cleanup. sokol-zig#57)
  • odin (Fixed for sokol-gfx pass cleanup. sokol-odin#8)
  • nim (Fixes for sokol-gfx pass cleanup. sokol-nim#28)
  • rust (Fixes for sokol-gfx pass cleanup. sokol-rust#22)
• fix dependent projects
  • samples (Fixes for sokol-gfx pass cleanup. sokol-samples#137)
  • pacman.c (Fixes for sokol_gfx.h pass cleanup pacman.c#12)
  • chips (Fixes for sokol-gfx pass cleanup chips-test#33)
  • v6502r (Fixes for sokol-gfx pass cleanup v6502r#24)
  • pacman.zig (Fixes for sokol-gfx pass cleanup. pacman.zig#23)
  • kc85.zig (Fixes for sokol-gfx pass cleanup kc85.zig#4)
  • doom (Fixes for sokol-gfx pass cleanup. doom-sokol#1)
  • cimgui-starter-kit (Fixes for sokol-gfx pass cleanup (and general dep update) cimgui-sokol-starterkit#18)
  • qoiview (Fixes for sokol-gfx pass cleanup (and general sokol header update) qoiview#10)
• fix sokol_app.h documentation
• fix sokol_gfx_imgui.h documentation
• fix sokol_gfx.h documentation
  • sg_setup() + sokol_glue.h()
  • sg_swapchain
  • sg_environment
  • sg_attachments
  • sg_attachments_desc
  • rewrite render passes section
• test
  • macOS + Metal
  • macOS + GL
  • iOS + Metal
  • iOS + GL
  • Android
  • Windows + D3D11
  • Windows + GL
  • Web + WebGL2
  • Web + WebGPU
• update changelog
• update readme
  • merge sokol_gfx.h and sokol_app.h section and change the hello-triangle to use sokol_app.h

Merged:

• sokol-zig
• sokol-odin
• sokol-nim
• sokol-rust
• sokol-samples
• pacman.c
• pacman.zig
• kc85.zig
• doom
• cimgui-starter-kit
• v6502r
• chips-test
• 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. 😞

• Improvements and fixes kassane/sokol-d#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.