Ensure we pick the right gpu card in the example backend

[arjo129]

Connections
fixes #6522

Description
This is my first time contributing to this project, so it may be that I'm doing something wrong. Essentially, we retain the old behavior if we use the environment variable to select our gpu. Otherwise we first try to match required features prior to selecting an adapter.

Testing

Just run the example as done before.

Checklist

• Run cargo fmt.
• Run taplo format.
• 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.

[Wumpf]

thanks for your contribution! looks good to me!

[Wumpf]

ah but I think this will fail wasm ci because enumerate_adapters is native only, let's see

[Wumpf]

yeah, this still needs special handling for wasm (and fix unused warnings) - that checklist on the PR template is there for a reason ;-)

[arjo129]

Thanks @Wumpf for pointing that out. Sorry about that. I've fixed wasm support by refactoring this logic out into a seperate function.

[Wumpf]

no worries!
a little bit much c&p for my taste, but this will do just fine :)