New wgpu native

[almarklein]

Preparations

• Wrap up outstanding PR's.
• Release wgpu-py.

Upstream

• Update wgpu-native to wgpu-core 0.19.4. Already done.
• Update wgpu-native to wgpu-core 0.20.0. Trying in Update to wgpu-core 0.20.0 gfx-rs/wgpu-native#387 -> another day

Update to latest IDL

Not now.

Update to latest wgpu-native

• Run python download-wgpu-native.py --version xx to download the latest webgpu.h and DLL.
• Run python codegen to apply the automatic patches to the code.
• It may be necessary to tweak the hparser.py to adjust to new formatting.
• Diff the report for new differences to take into account.
• Diff wgpu_native/_api.py to get an idea of what structs and functions have changed.
• Go through all FIXME comments that were added in _api.py:
  * Apply any necessary changes.
  * Remove the FIXME comment if no further action is needed, or turn into a TODO for later.
• Run python codegen again to validate that all is well. Repeat the steps above if necessary.
• Make sure that the tests run and provide full coverage.
• Make sure that the examples all work.
• Make sure that pygfx works (again).
• Update release notes for changes in behavior.

Wrapping up

• Update pygfx. (no need)
• Release new wgpu-py.
• Release new pygfx, maybe.

[almarklein]

Made this because I hoped it fixed pygfx/pygfx#763. It did not. Can update nonetheless.

[almarklein]

Ready. Let's bump it.

[almarklein]

@Korijn can this one get approval too?