[TouchLatency] Add intent extra arg to set the mode on start

To make automation testing with the TouchLatency app more reliable, add
an extra intent argument that lets you change the action mode to BALL
when the app launches. Currently, we have scripting that uses
uiautomator to get the action_settings button coordinates in order to
switch the mode.  This can be flaky if the options menu is open or the
app is already in BALL mode due to a previous state.

With this change, you can launch the app in bouncy ball mode with the
following command:

  adb shell am start -n \
    com.prefabulated.touchlatency/.TouchLatencyActivity \
    --ei action_mode_on_create 1

Bug: 414642844
Flag: TEST_ONLY
Test: verify with various intent extra args
Change-Id: Ib697887e467ff4e92051ad6a347c3991b2e1d7f8