internal/rosa: pass stage alongside state

This cleans up many function signatures.

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

internal/rosa/dtc.go

@@ -2,12 +2,12 @@ package rosa
 
 import "hakurei.app/internal/pkg"
 
-func (t Toolchain) newDTC(s *S) (pkg.Artifact, string) {
+func (t Toolchain) newDTC() (pkg.Artifact, string) {
 	const (
 		version  = "1.7.2"
 		checksum = "vUoiRynPyYRexTpS6USweT5p4SVHvvVJs8uqFkkVD-YnFjwf6v3elQ0-Etrh00Dt"
 	)
-	return s.NewPackage(t, "dtc", version, newTar(
+	return t.NewPackage("dtc", version, newTar(
 		"https://git.kernel.org/pub/scm/utils/dtc/dtc.git/snapshot/"+
 			"dtc-v"+version+".tar.gz",
 		checksum,