Move global window indices to constexpr #2097

Job	Run time
g2.dat	7s
Check code formatting	40s
Lint Commit Message	0s
Check changelog formatting	7s
macOS (x64) using CMake	13m 47s
Windows (win32)	7m 38s
macOS (arm64) using CMake	11m 50s
Windows (x64)	7m 13s
Linux (x86_64, AppImage)	8m 11s
Windows (arm64)	7m 51s
Windows (win32) using mingw	8m 40s
Linux (x86_64, focal, portable)	8m 38s
Linux (x86_64, jammy, portable)	9m 19s
Android	7m 50s
Linux (x86_64, bullseye, portable)	9m 2s
Linux (i686, focal, portable)	8m 28s
Linux (Debug, [http, network, flac, vorbis OpenGL] disabled) using clang	11m 25s
Linux (Debug) using clang, coverage enabled	12m 47s
Linux (docker)	0s
macOS universal app bundle	48s
	2h 14m 21s

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