feat: add perf walltime support #150

Job	Run time
bazel-integration-tests (instrumentation, ubuntu-latest)	2m 31s
bazel-integration-tests (walltime, codspeed-macro)	2m 27s
cmake-integration-tests (walltime, codspeed-macro)	3m 19s
cmake-integration-tests (instrumentation, ubuntu-latest)	1m 33s
tests	10s
cmake-integration-tests (off, ubuntu-latest)	54s
windows-cmake-build (walltime)	2m 10s
bazel-integration-tests (off, ubuntu-latest)	50s
windows-cmake-build (off)	1m 58s
windows-bazel-build (walltime)	1m 30s
windows-bazel-build (off)	1m 16s
	18m 38s

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