Update to 1.39.2

Also too the opportunity to rewrite the build script since there was a
change in the build steps (mainly how the product JSON is inserted) and
to get the build changes out of the patch. It also no longer relies on
external caching (we'll want to do this within CI instead).

scripts/tsconfig.json

@@ -0,0 +1,17 @@
+{
+	"compilerOptions": {
+		"module": "commonjs",
+		"moduleResolution": "node",
+		"noImplicitAny": true,
+		"experimentalDecorators": true,
+		"noImplicitReturns": true,
+		"noUnusedLocals": true,
+		"noImplicitThis": true,
+		"alwaysStrict": true,
+		"strictBindCallApply": true,
+		"strictNullChecks": true,
+		"forceConsistentCasingInFileNames": true,
+		"baseUrl": ".",
+		"target": "esnext"
+	}
+}