Make refreshNetwork async (#1182)

The internal method `refreshNetwork` has been made async. The method
already called an asynchronous method internally, but it was not
`await`-ed. Now it is.

This method is only being called from within synchronous functions.
They will be made async in later PRs.

Because the async call was the last operation, this change effectively
has no functional impact.

This relates to #1176

packages/network-controller/src/NetworkController.ts

@@ -288,14 +288,14 @@ export class NetworkController extends BaseControllerV2<
     };
   }
 
-  private refreshNetwork() {
+  private async refreshNetwork() {
     this.update((state) => {
       state.network = 'loading';
       state.networkDetails = {};
     });
     const { rpcTarget, type, chainId, ticker } = this.state.providerConfig;
     this.configureProvider(type, rpcTarget, chainId, ticker);
-    this.lookupNetwork();
+    await this.lookupNetwork();
   }
 
   private registerProvider() {