refactor: separate transit sources and request service

package.json

@@ -237,6 +237,8 @@
     },
     "./sources/transit": "./src/data/transitProxy.js",
     "./layers/transit": "./src/layers/transit/index.js",
-    "./layers/transit/standalone": "./src/data/transit.js"
+    "./layers/transit/standalone": "./src/data/transit.js",
+    "./layers/transit/source": "./src/layers/transit/source.js",
+    "./sources/transit-service": "./src/sources/transitService.js"
   }
 }