[native] [33/34] ReactNav6: Update HeaderTitle to use flex positioning

Summary:
The relevant part here is actually just removing headerTitleContainerStyle... without that, the HeaderTitle was way too narrow.

But I also did the work to forward props along since it seemed like the right thing.

Context on change here.

Depends on D5425

Test Plan: Flow + ran the app on my phone and played around with it

Reviewers: atul, tomek, bartek

Reviewed By: atul

Subscribers: abosh

Differential Revision: https://phab.comm.dev/D5426