internal/rosa: helpers for common url formats

This cleans up call site of NewPackage.

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

internal/rosa/ninja.go

@@ -21,17 +21,17 @@ python3 /usr/src/ninja/configure.py \
 mkdir -p /work/system/bin/
 cp ninja /work/system/bin/
 `, pkg.Path(AbsUsrSrc.Append("googletest"), false,
-		pkg.NewHTTPGetTar(
-			nil, "https://github.com/google/googletest/releases/download/"+
-				"v1.16.0/googletest-1.16.0.tar.gz",
-			mustDecode("NjLGvSbgPy_B-y-o1hdanlzEzaYeStFcvFGxpYV3KYlhrWWFRcugYhM3ZMzOA9B_"),
+		newFromGitHubRelease(
+			"google/googletest",
+			"v1.16.0",
+			"googletest-1.16.0.tar.gz",
+			"NjLGvSbgPy_B-y-o1hdanlzEzaYeStFcvFGxpYV3KYlhrWWFRcugYhM3ZMzOA9B_",
 			pkg.TarGzip,
 		)), pkg.Path(AbsUsrSrc.Append("ninja"), true, t.NewPatchedSource(
-		"ninja", version, pkg.NewHTTPGetTar(
-			nil, "https://github.com/ninja-build/ninja/archive/refs/tags/"+
-				"v"+version+".tar.gz",
-			mustDecode(checksum),
-			pkg.TarGzip,
+		"ninja", version, newFromGitHub(
+			"ninja-build/ninja",
+			"v"+version,
+			checksum,
 		), false,
 	))), version
 }