TouchInputMapper: Cancel ongoing gesture when resetting

Since reset is called when a device is being enabled or disabled, if it
doesn't cancel ongoing gestures, there is a possiblity of seeing an
inconsistent gesture stream.

Also, make sure we send FLAG_CANCELED when sending ACTION_CANCEL from
TouchInputMapper.

Bug: 245989146
Test: atest inputflinger_tests
Change-Id: I9921eee9acf365b28d97f3fbe9b4d6cd15fe7087