register: Dispatch REGISTER_START just before we start /register.

With the goal that REGISTER_START and REGISTER_COMPLETE are tight
bookends around the code responsible for making the /register
request.

We hope this is NFC; the only cases where it wouldn't be are when
`getAuth` and/or `getHaveServerData` throw an error.

`getAuth` would be the natural one to worry about, but we really
don't expect `doInitialFetch` to be called unless we have an active,
logged-in account.

Author: chrisbobbe

src/message/fetchActions.js

@@ -448,11 +448,11 @@ export async function tryFetch<T>(
  * (`SearchMessagesScreen`).
  */
 export const doInitialFetch = (): ThunkAction<Promise<void>> => async (dispatch, getState) => {
-  dispatch(registerStart());
   const auth = getAuth(getState());
 
   const haveServerData = getHaveServerData(getState());
 
+  dispatch(registerStart());
   let initData: InitialData;
   try {
     initData = await tryFetch(