refactor(layers/prometheus): provide builder APIs #1663

Job	Run time
build_all_features	4m 37s
build_all_platforms (ubuntu-latest)	2m 28s
build_default_features (ubuntu-latest)	51s
build_all_platforms (macos-latest)	2m 43s
build_under_wasm	45s
build_default_features (macos-latest)	49s
build_all_platforms (windows-latest)	5m 45s
build_default_features (windows-latest)	2m 46s
check_clippy	3m 36s
check_docs	3m 5s
check_msrv	33s
unit	7m 28s
	35m 26s

Provide feedback