Update App Handle strings to announce Desktop View

Currently there is no indication that users are actually in desktop mode
when using Talkback, so updating the app handle content description to
announce "<app name> - Desktop View". Also updating the announce text
for the app handle buttons to use "Desktop View" insted of "desktop
windowing mode"

Bug: 329030507
Test: manual testing
Flag: EXEMPT bug fix
Change-Id: I85aec10b173e6f8d1743e7550d0189a49cac100b