Bouncer a11y - Make message area selectable

By default, focus should go to the input area for PIN views.
However, the user should still be able to navigate to the message
area text to prompt readout.

Fixes: 379016691
Test: manual - use talkback
Flag: EXEMPT a11y fix
Change-Id: I2c566148dd5c12be6222dfb85c43b447772a1ec9