Add format conversions for WebGPU formats. This CL adds a Format class, as well as a generator script to generate methods to map between WebGPU and ANGLE formats. Fallback mappings are listed but this CL only implements support for required webgpu formats. Bug: angleproject:344814096 Change-Id: I2588a57353eafc4e87f40df3bbe3f9375e5ed8c6 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5598178 Reviewed-by: Matthew Denton <mpdenton@chromium.org> Commit-Queue: Liza Burakova <liza@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>