Need `CodeQuality` issue template

## What problem does this solve or what need does it fill?

Users cannot create issues for code quality, only for bugs and new features. For example #5439 is neither a bug (everything works), nor a feature request (the API would possibly change a bit, but the feature set won't).

## What solution would you like?

Add a new GitHub template for code quality.

## What alternative(s) have you considered?

Ping @alice-i-cecile for each new code quality Issue to remove the `C-Bug` tag and add the `C-CodeQuality` one.

## Additional context

Surprisingly, Alice seem to prefer the template approach... `¯\_(ツ)_/¯`