Rust

Eliminate `regex` and `once_cell` dependencies. #1167

Job	Run time
build_bin_spec (nightly)	1m 55s
build_lib_test (nightly)	1m 0s
build_bin_spec (beta)	1m 20s
build_wasm (nightly)	54s
build_lib_test (beta)	1m 38s
lockfile	2m 15s
build_bin_spec (stable)	1m 36s
build_lib_test (stable)	2m 10s
build_wasm (beta)	49s
build_bin_spec ($MSRV)	2m 58s
build_lib_test ($MSRV)	2m 36s
build_wasm (stable)	42s
build_wasm ($MSRV)	1m 57s
no_features_build_test (nightly)	49s
no_features_build_test (beta)	43s
no_features_build_test (stable)	59s
clippy_format	2m 34s
no_features_build_test ($MSRV)	1m 37s
	28m 32s

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