feat(services/obs): support user defined metadata #2141

Job	Run time
build_all_features	4m 23s
build_all_platforms (ubuntu-latest)	2m 17s
build_all_platforms (macos-latest)	2m 3s
build_all_platforms (windows-latest)	2m 12s
build_default_features (ubuntu-latest)	34s
build_under_wasm	46s
build_default_features (macos-latest)	38s
check_clippy	3m 59s
build_default_features (windows-latest)	1m 43s
check_docs	3m 14s
check_msrv	33s
unit	5m 3s
	27m 25s

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