Extract & re-use filter_targets in cargo_compile
Extract & re-use filter_targets in cargo_compile

Also drop part of the docs in `list_rule_targets`, as that info is now on `Proposal`.

tsurai/cargo,nipunn1313/cargo,tsurai/cargo,vojtechkral/cargo,rustyhorde/cargo,tshepang/cargo,tshepang/cargo,eminence/cargo,tshepang/cargo,vojtechkral/cargo,rust-lang/cargo,tsurai/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo,nipunn1313/cargo,eminence/cargo,tsurai/cargo,rust-lang/cargo,tshepang/cargo,vojtechkral/cargo,tsurai/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo,rustyhorde/cargo,vojtechkral/cargo,rustyhorde/cargo,rust-lang/cargo