Separate a11y and autofill view ids

Autofill seems to need IDs to be preserved across things
like configuration changes, while accessibility will not
function without views with unique ids. Separating out the
two types of IDs. We can re-combine them once it's clear
that both demands can be satisfied.

Bug: 62301218
Test: Run a11y and autofill CTS, and verify that the play
store app functions with TalkBack after a screen rotation.

Change-Id: I17a99de2874768fc0ade3aa354130dd1f6b4cd7e