Add ImGui support #7054

Job	Run time
Update LFS data cache	45s
external-build	2m 11s
android (armeabi-v7a)	2m 13s
android (arm64-v8a)	2m 16s
android (x86)	2m 22s
android (x86_64)	2m 18s
macos_arm (commit, no-bundle, no-static)	7m 21s
linux (commit, standard)	9m 40s
macos_arm (v9.3.1, no-bundle, no-static)	7m 6s
linux (v9.3.1, standard)	6m 16s
macos_arm (commit, bundle, no-static)	8m 56s
macos (commit)	17m 29s
python-packaging (ubuntu-latest)	4m 24s
macos_arm (commit, no-bundle, static)	7m 19s
linux (v9.2.6, standard)	6m 26s
macos (v9.3.1)	14m 44s
python-packaging (windows-latest)	6m 4s
linux (egl, commit, raytracing, optional-deps, no-exclude-deprecated, egl, no-static)	9m 52s
python-packaging (macos-13)	4m 4s
macos (v9.2.6)	13m 30s
linux (osmesa, commit, raytracing, optional-deps, no-exclude-deprecated, osmesa, no-static)	9m 30s
windows (commit, no-static)	15m 52s
linux (exclude_deprecated, commit, raytracing, optional-deps, exclude-deprecated, auto, no-static)	9m 25s
windows (v9.3.1, no-static)	10m 1s
linux (no_optional_deps, commit, no-raytracing, no-optional-deps, no-exclude-deprecated, auto, no...	6m 44s
coverage	9m 28s
windows (v9.2.6, no-static)	10m 33s
linux (static_libs, commit, no-raytracing, optional-deps, no-exclude-deprecated, auto, static)	8m 38s
windows (commit, static)	15m 7s
sanitizer (address)	10m 55s
static-analysis	4m 52s
sanitizer (thread)	11m 40s
sanitizer (undefined)	8m 25s
	4h 26m 26s

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