internal/rosa: pass stage alongside state

This cleans up many function signatures.

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

internal/rosa/libexpat.go

@@ -6,12 +6,12 @@ import (
 	"hakurei.app/internal/pkg"
 )
 
-func (t Toolchain) newLibexpat(s *S) (pkg.Artifact, string) {
+func (t Toolchain) newLibexpat() (pkg.Artifact, string) {
 	const (
 		version  = "2.8.1"
 		checksum = "iMEtbOJhQfGof2GxSlxffQSI1va_NDDQ9VIuqcPbNZ0291Dr8wttD5QecYyjIQap"
 	)
-	return s.NewPackage(t, "libexpat", version, newFromGitHubRelease(
+	return t.NewPackage("libexpat", version, newFromGitHubRelease(
 		"libexpat/libexpat",
 		"R_"+strings.ReplaceAll(version, ".", "_"),
 		"expat-"+version+".tar.bz2",