[native] Fix handleCurrentUserFID querying for current user's FID

Summary: This addresses [ENG-9230](https://linear.app/comm/issue/ENG-9230/cant-see-option-to-manage-farcaster-tags-on-web). The cause was a simple error from D12569. Flow failed to catch it because it wasn't sure that `currentUserID` wasn't the string `"identities"`.

Test Plan: I deployed a release build to my iOS device and confirmed that the Profile -> Farcaster account screen now showed a linked Farcaster account.

Reviewers: varun, will

Reviewed By: varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13313

lib/components/farcaster-data-handler.react.js

@@ -187,8 +187,10 @@ function FarcasterDataHandler(props: Props): React.Node {
       return;
     }
 
-    const currentUserIdentityObj = await findUserIdentities([currentUserID]);
-    const identityFID = currentUserIdentityObj[currentUserID]?.farcasterID;
+    const { identities: userIdentities } = await findUserIdentities([
+      currentUserID,
+    ]);
+    const identityFID = userIdentities[currentUserID]?.farcasterID;
 
     if (identityFID) {
       dispatch({