Add examples for instance extras

[Vipitis]

This was mentioned in reply #718 (review)

PR adds two examples regarding instance extras:

• Using DXC(over FXC) on Windows, includes a script to download the required library files.
• Debugging using a graphics debugger like RenderDoc, includes a portable variant with a .cap file: works when your OS is setup to open .cap file with RenderDoc. Adds annotation and labels to the cube example.
• documents the function in docs.

todos:

• insert debug markers for the example
• add labels to the example so they show up during debugging
• fix more typos
• add hyperlinks to other parts of the docs
• update guide docs debug section?
• file issue with Dxc not using debug flags in wgpu-core (perhaps in v26?) ref: unable to get debug flags with Dxc gfx-rs/wgpu-native#487
• resolve arch, if needed?

[Vipitis]

while renderdoc has a python api, it's complex to build and package with modern python versions. So this might look like a workaround but I feel like that is actually quite convenient to use... making it work on linux sounds plausible.

[Vipitis]

this is quite a messy branch with the changes to the example on main... is there still interest to have the other parts of the PR (examples, docs, download scripts).

I can fix the the extra bind group nesting and labels for the cube example in a different PR which should be a bit easier.

[almarklein]

The conflicts in cube.py don't look too bad ... but ok if you want to contribute parts of this PR in pieces if that's easier!

[Vipitis]

I think I broke it more by trying to be clever... will try again tomorrow.

[Vipitis]

the branch in #760 should merge correctly