layers: Add VK_KHR_maintenance8 #10277

Job	Run time
code-format	31s
check_vvl	1m 5s
androidOnLinux	7m 28s
chromium (target_os="linux" target_cpu="x64")	7m 58s
android (arm64-v8a, ON, c++_shared)	9m 12s
chromium (target_os="android" target_cpu="arm64")	11m 18s
android (armeabi-v7a, OFF, c++_static)	4m 21s
Ubuntu Backcompat	10m 12s
linux (address sanitizer, debug, robinhood ON )	33m 19s
linux (address sanitizer, release, robinhood ON )	27m 2s
linux (thread sanitizer, release, robinhood ON )	10m 41s
linux (address sanitizer, release, robinhood OFF )	27m 51s
mingw	8m 29s
windows (amd64)	10m 24s
windows (amd64_x86)	10m 5s
iOS	4m 50s
androidUpload	0s
windowsUpload	0s
linux Upload	0s
	3h 4m 46s

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