[native] Pass customKeyName to dispatchActionPromise in selectFromGalleryAndUpdateThreadAvatar

Summary:
We want to be able to use createLoadingStatusSelector to track LoadingStatus of avatar update request. However, the changeThreadSettings action and endpoint also handles updating thread name, color, avatar, etc.

We don't want to, for example, display ActivityIndicator over avatar when thread color or some unrelated setting is being changed.

Followed what @ginsu did in useSaveThreadAvatar.

Test Plan: NA, will be tested implicitly in next diff.

Reviewers: ashoat, ginsu

Reviewed By: ginsu

Subscribers: tomek, ginsu

Differential Revision: https://phab.comm.dev/D7545