Implement tight / loose #1110

Job	Run time
no_features_build_test (nightly)	29s
build_bin_spec (nightly)	1m 8s
no_features_build_test (beta)	31s
build_lib_test (nightly)	52s
build_bin_spec (beta)	1m 6s
no_features_build_test (stable)	43s
build_wasm (nightly)	53s
build_lib_test (beta)	1m 21s
build_bin_spec (stable)	1m 1s
no_features_build_test ($MSRV)	2m 21s
build_lib_test (stable)	1m 18s
build_wasm (beta)	53s
build_bin_spec ($MSRV)	3m 6s
build_lib_test ($MSRV)	3m 37s
build_wasm (stable)	49s
build_wasm ($MSRV)	2m 52s
clippy_format	2m 30s
lockfile	1m 4s
	26m 34s

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