Change get_preferred_format to get_supported_formats

[stevenhuyn]

Connections
Closes #2718

Description
Converted everything related to get_preferred_format -> Option<TextureFormat> to get_supported_formats -> Option<Vec<TextureFormat>>

Converted the web version to return the set of texture formats defined by https://gpuweb.github.io/gpuweb/#supported-context-formats

Testing
I ran cargo nextest run --no-fail-fast

[stevenhuyn]

Trying to understand this error, when get_preferred_format doesn't exist in either this branch nor the web_sys crate.

error[E0599]: no method named `get_supported_formats` found for struct `GpuCanvasContext` in the current scope
    --> wgpu\src\backend\web.rs:1198:14
     |
1198 |             .get_supported_formats(&adapter.0)
     |              ^^^^^^^^^^^^^^^^^^^^^ help: there is an associated function with a similar name: `get_preferred_format`

For more information about this error, try `rustc --explain E0599`.

[cwfitzgerald]

All that stuff is behind the web_sys_unstable_apis cfg, so doesn't show up on docs.rs.

[cwfitzgerald]

Looks good, thanks for tackling this, some comments

[cwfitzgerald]

One more change then we're good

[cwfitzgerald]

Thanks!