Show toolbar when DEG/RAD mode matters

Bug: 27926287
Bug: 28086262

Continue to show the toolbar when entering a formula containing trig
function calls.

This also changes the toolbar hiding logic a bit to make physical
keyboard input more like button presses.

No longer makes the tool bar visible on a long press, reserving
that for COPY or PASTE.

Change-Id: I30cb3d747e45b8fe24e35b20805a1d04bdf7b8c9