Add Metrics API #1461

Job	Run time
Xcode Build for iOS	56s
Lint	27s
Linux (old gcc, 32-bit)	1m 20s
Linux (new gcc)	6m 16s
Linux (clang + asan + llvm-cov)	6m 59s
Linux (clang + kcov)	1m 25s
Linux (gcc + code-checker + valgrind)	2m 8s
macOS (xcode llvm)	15m 27s
macOS (xcode llvm + universal)	24m 18s
macOS (clang + asan + llvm-cov)	18m 53s
Windows (old VS, 32-bit)	12m 16s
Windows (latest)	10m 0s
LLVM-Mingw	14m 17s
Android (old API/NDK)	4m 15s
Android (new API/NDK)	6m 1s
Create Release Archive	0s
	2h 4m 58s

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