entry: fix scroll region jumping issue

entry: fix scroll region jumping issue

When elm_entry takes focus by mouse clicked,
scroll region should be decided by new cursor position.

1. *_on_focus_region
   *_on_focus_region will be called before updating cursor position.
   So, elm_entry need to predict cursor position by mouse down and move.

2. _show_region_hook
   The geometry from elm_widget_show_region_get() is not proper when
   the hook function is called. We need to get cursor's geometry everytime.
   Becasue, the geometry is relative. Whenever scroll region updated,
   the geometry also has to be updated.

* dependancy warrning :
  - efl
  "edje entry: keep cursor position on mouse down and move"
  https://review.tizen.org/gerrit/#/c/96783/

@tizen_fix

Change-Id: I5c74b95de32701088a9031423939ce23909c4956