Switch main's route handlers to be static functions (#2712)

src/main/utils/http-responses.ts

@@ -0,0 +1,15 @@
+import http from "http";
+
+export function respondJson(res: http.ServerResponse, content: any, status = 200) {
+  respond(res, JSON.stringify(content), "application/json", status);
+}
+
+export function respondText(res: http.ServerResponse, content: string, status = 200) {
+  respond(res, content, "text/plain", status);
+}
+
+export function respond(res: http.ServerResponse, content: string, contentType: string, status = 200) {
+  res.setHeader("Content-Type", contentType);
+  res.statusCode = status;
+  res.end(content);
+}