Re-enable building the editor

[pzychotic]

Pull Request Type

• GitHub Workflow changes
• Documentation or Wiki changes
• Build and Dependency changes
• Runtime changes
  • Render changes
  • Audio changes
  • Input changes
  • Network changes
  • Other changes

Description

CMAKE_SYSTEM_NAME isn't defined before the project call, so moved the option below it. Actually moved all options to keep them together and hopefully prevent similar problems in the future when adding new stuff.
Also put all the editor related projects into a single if scope.

This broke already a while ago, when the vcpkg changes where introduced and the project call moved down.
I just noticed it now after deleting the whole build directory and starting fresh, since the option was still in my CMakeCache all that time.

Related Issues

Screenshots (if applicable)

Checklist

• I have tested my changes locally and verified that they work as intended.
• I have documented any new or modified functionality.
• I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

Additional Comments

[winterheart]

I remember fixing this once before, probably in one of my countless branches that didn't make it into the main branch...