autoclick: Refactor and extract drag functions

Refactored the code to extract three drag methods, in preparation for adding auto-drag support, which will also use these functions.

Final Video: http://shortn/_hk0FUZo6BK

Bug: b/416050648
Test: atest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: I20b452e0adb71e8d7ce562c134dccb4245a06d0f