master's new xtext_tests target compiles xtext.c on its own with only
GTK linked, so hexcolor_parse cannot live in util.c. Keep it in a
dependency-free hexcolor.c that both test targets compile, and register
it in the Visual Studio project for the Windows build.
Claude-Session: https://claude.ai/code/session_01Jxd4AknGzdAENADWAGHCzx
