feat: add isInitialized (#150)

* add isInitialized

* Update src/main/server.ts

---------

Co-authored-by: Erick Zhao <erick@hotmail.ca>

src/main/index.ts

@@ -1 +1 @@
-export { initialize, enable } from "./server";
+export { initialize, isInitialized, enable } from "./server";

src/main/server.ts

@@ -358,6 +358,11 @@ const logStack = function (contents: WebContents, code: string, stack: string |
 }
 
 let initialized = false
+
+export function isInitialized() {
+  return initialized
+}
+
 export function initialize() {
   if (initialized)
     throw new Error('@electron/remote has already been initialized')