Cleanup Surface API

[cwfitzgerald]

Checklist

• Run cargo clippy.
• Run RUSTFLAGS=--cfg=web_sys_unstable_apis cargo clippy --target wasm32-unknown-unknown if applicable.
• Add change to CHANGELOG.md. See simple instructions inside file.

Connections

First step of #2869.

Description

Cleans up the current surface capabilities interface so that extension is easier. Commits are standalone and should be rebased.

Testing
Ran the examples.

[codecov-commenter]

Codecov Report

Merging #3236 (5d2035b) into master (d4b1d57) will increase coverage by 0.10%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3236      +/-   ##
==========================================
+ Coverage   64.64%   64.74%   +0.10%     
==========================================
  Files          82       82              
  Lines       39501    39436      -65     
==========================================
- Hits        25534    25533       -1     
+ Misses      13967    13903      -64     

Impacted Files	Coverage Δ
wgpu-core/src/device/mod.rs	66.64% <0.00%> (+0.31%)	⬆️
wgpu-core/src/instance.rs	65.92% <0.00%> (+2.13%)	⬆️
wgpu-types/src/lib.rs	87.51% <0.00%> (-0.42%)	⬇️
wgpu/src/backend/direct.rs	55.40% <0.00%> (+0.59%)	⬆️
wgpu/src/lib.rs	50.55% <0.00%> (+0.22%)	⬆️
wgpu-core/src/hub.rs	60.67% <0.00%> (-0.16%)	⬇️

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