Since we support `apply` DSL in the `patch` block, external
patch files could be any compressed archive. As result, it
could introduce dependencies like xz, 7z etc.

Add the resource of ExternalPatch to dependency_collector, so
we could track these resource dependencies.

Closes Homebrew/homebrew#50318.

Signed-off-by: Xu Cheng <xucheng@me.com>