Checklist

• cargo clippy reports no issues
• cargo doc reports no issues
• cargo deny issues have been fixed or added to deny.toml
• Human-readable change descriptions added to CHANGELOG.md under the "Unreleased" heading.
  • If the change does not affect the user (or is a process change), preface the change with "Internal:"
  • Add credit to yourself for each change: Added new functionality. @githubname

Description

Implemented wgpuCommandEncoderClearTexture, and uncommented the ClearTexture feature.
I added a WGPUImageSubresourceRange struct to wgpu.h which mimicks the same struct in wgpu. I didn't find anything else that has the same/similar fields (e.g. WGPUTexelCopyTextureInfo and such don't cut it), so I added a new struct.