## Summary

Closes #64945.

Add UTF-8 header to `rc_content` which is passed to rc.exe as args.

## Testing

Before this change: build failed with `thread 'main' (7344) panicked at
crates\windows_resources\src\windows_resources.rs:122:10:
called `Result::unwrap()` on an `Err` value: Failed("RC.EXE failed to
compile specified resource file")`

Alfter this change: build success.

## Self-review

- [x] I've reviewed my diff for quality, security, reliability, and
performance.
- [x] UI changes follow the
[checklist](https://zed.dev/docs/development/ui-checklist).
- [x] Tests cover the new or changed behavior.

Release Notes:

- N/A

Co-authored-by: Kunall Banerjee <hey@kimchiii.space>