feat(layer/otelmetrics): add OtelMetricsLayer #2319

Job	Run time
check_clippy	4m 18s
check_docs	3m 26s
build_all_features	5m 6s
build_all_platforms (ubuntu-latest)	2m 58s
build_all_platforms (macos-latest)	2m 31s
build_default_features (ubuntu-latest)	38s
build_under_wasm	42s
build_all_platforms (windows-latest)	6m 13s
build_default_features (macos-latest)	56s
build_default_features (windows-latest)	2m 7s
check_msrv	39s
unit	7m 2s
	36m 36s

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