[native] Create a LinkedDevicesHeaderRightButton that will open the QR scanner

Summary:
We want to allow the react navigation header right button to be pressed in order to open the QR code scanner for the new login flow. The onPress action will come in a following diff, this just adds the header right component to the new LinkedDevices screen.

I know I could have inlined the headerRight component probably in profile.react.js, but since I plan to add some additional checks (i.e. if the device is on a simulator) when the header right is pressed before opening the QR code scanner, I thought it would be cleaner extracting it to its own component file.

Part of ENG-4476

Depends on D8764

Test Plan:
Confirmed that the header right appears in the LinkedDevices screen

Reviewers: atul, ginsu, varun, tomek

Reviewed By: ginsu

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8769