This is an Android continuation of bc95c00. We now call
InputDetector::Update immediately after receiving an input event from
Android instead of periodically calling it in a sleep loop. This
improves detection of very short inputs, which are especially likely to
occur for volume buttons on phones (or at least on my phone) if you
don't intentionally keep them held down.

It's missing a lot of features from the PC version for now, like
buttons for inserting functions and the ability to see what the
expression evaluates to. I mostly just wanted to get something in
place so you can set up rumble.

Co-authored-by: Charles Lombardo <clombardo169@gmail.com>