Add ImGui support #6974

Job	Run time
external-build	2m 16s
Update LFS data cache	1m 48s
android (armeabi-v7a)	2m 5s
android (arm64-v8a)	2m 19s
android (x86)	2m 23s
android (x86_64)	2m 24s
coverage	7m 33s
macos (commit)	14m 7s
macos_arm (commit, no-bundle, no-static)	4m 47s
macos (v9.3.1)	12m 29s
linux (commit, standard)	8m 8s
macos_arm (v9.3.1, no-bundle, no-static)	6m 24s
macos (v9.2.6)	12m 20s
linux (v9.3.1, standard)	6m 29s
python-packaging (ubuntu-latest)	3m 25s
macos_arm (commit, bundle, no-static)	5m 36s
linux (v9.2.6, standard)	5m 46s
python-packaging (windows-latest)	5m 17s
macos_arm (commit, no-bundle, static)	4m 50s
linux (egl, commit, raytracing, optional-deps, no-exclude-deprecated, egl, no-static)	7m 43s
python-packaging (macos-13)	3m 45s
sanitizer (address)	10m 12s
linux (osmesa, commit, raytracing, optional-deps, no-exclude-deprecated, osmesa, no-static)	8m 15s
sanitizer (thread)	11m 23s
linux (exclude_deprecated, commit, raytracing, optional-deps, exclude-deprecated, auto, no-static)	8m 0s
static-analysis	4m 34s
sanitizer (undefined)	7m 46s
windows (commit, no-static)	10m 13s
linux (no_optional_deps, commit, no-raytracing, no-optional-deps, no-exclude-deprecated, auto, no...	5m 45s
windows (v9.3.1, no-static)	10m 5s
linux (static_libs, commit, no-raytracing, optional-deps, no-exclude-deprecated, auto, static)	7m 50s
windows (v9.2.6, no-static)	9m 55s
windows (commit, static)	10m 21s
	3h 46m 13s

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