Provide an option in KeyguardIndicationTextView to always announce the text being displayed

Fixes: 281765653
Test: verified manually
  1. flip the flag on
  2. enroll face and fp
  3. enable talkback on
  4. go to lockscreen
  5. try incorrect fingerprint
  6. cover face and try face unlock
  7. plug in charger and unplug charger
  8. try incorrect face
  9. face unlock unsuccessfully
  10.slightly touch udfps to show the press firmly on sensor message
  11.all the messages in the keyguard indication area must be read out loud even if it happens within a period of 30seconds.
Change-Id: I8e8328cc133ca126c3eb40c0623e1dfc0eafbb04