internal/rosa: pass stage alongside state

This cleans up many function signatures.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/libffi.go

@@ -2,12 +2,12 @@ package rosa
 
 import "hakurei.app/internal/pkg"
 
-func (t Toolchain) newLibffi(s *S) (pkg.Artifact, string) {
+func (t Toolchain) newLibffi() (pkg.Artifact, string) {
 	const (
 		version  = "3.5.2"
 		checksum = "2_Q-ZNBBbVhltfL5zEr0wljxPegUimTK4VeMSiwJEGksls3n4gj3lV0Ly3vviSFH"
 	)
-	return s.NewPackage(t, "libffi", version, newFromGitHubRelease(
+	return t.NewPackage("libffi", version, newFromGitHubRelease(
 		"libffi/libffi",
 		"v"+version,
 		"libffi-"+version+".tar.gz",