CTS - add new api to send a key while holding another

* replaces the specific implementation for SHIFT+key in
  TimePickerTest with a new function in KeyEventUtil
* the new KeyEventUtil function can be used with any
  modifier key
* stops using instrumentation to send keys in TimePickerTest
  CTS

Bug: 30152462
Change-Id: I83c5d097bb0909c269eb0ff5147400bfd42b9923
2 files changed