Rename task input controller.

The TaskInputController class doesn't need to be tightly coupled with
the actual input method, so we should rename it and the methods to
correspond to the actual logic. For example, both tapping a task and
pressing the overview button on recents should launch a task and should
both use this logic.

Bug: 114136250
Test: Launch tasks, clear tasks, clear all
Change-Id: If4f7f1d6ee9b05ffaf65cb13df633679cc8efcbe