refactor: Remove metakey concept #2031

Job	Run time
build_all_features	5m 29s
build_all_platforms (ubuntu-latest)	2m 53s
build_all_platforms (macos-latest)	2m 19s
build_default_features (ubuntu-latest)	38s
build_default_features (macos-latest)	44s
build_default_features (windows-latest)	1m 48s
build_all_platforms (windows-latest)	6m 43s
build_under_wasm	45s
check_clippy	3m 59s
check_docs	3m 32s
check_msrv	32s
unit	6m 18s
	35m 40s

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