Reintroduce computepass->encoder lifetime constraint and make it opt-out via wgpu::ComputePass::forget_lifetime

[Wumpf]

Connections

• Part of the wider story of Lifetimes on RenderPass make it difficult to use.  #1453
• Follow-up to Remove lifetime dependency of ComputePass to its parent command encoder #5620

Description
As suggested on Matrix chat by @kpreid.

In #5620, wgpu::ComputePass lost its explicit lifetime constraint to wgpu::CommandEncoder. This constraint prevented use of the command encoder while a pass is recorded. This is still an error, but now a runtime error. While removing this lifetime is very useful especially for library authors, it also prevented trivial incorrect api usage, i.e. that PR was great but also created a massive footgun ;-).

Here, we remedy this issue by re-introducing the exact same lifetime constraint but making it opt-out with a zero-overhead forget_lifetime method.

Testing
Existing tests have been adjusted - compilation failed as expected without these adjustments!

Checklist

• Run cargo fmt.
• Run cargo clippy. If applicable, add:
  • --target wasm32-unknown-unknown
  • --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.

[kpreid]

You pinged me, so you get my review 😁

The most important comment in this review bundle is that I think the name make_static() needs work.

[Wumpf]

thanks again, I'm much happier with this now!

[ErichDonGubler]

AFAICT, controls to Approve this PR are inaccessible. But ✅ let it be known that I would do so after reading through this today. Thanks for the help, @kpreid!