gengrid: Added normal reorder type

gengrid: Added normal reorder type

Summary:
- Added Elm_Gengrid_Reorder_Type enum
- Added API elm_gengrid_reorder_type_set()
- Implemented the normal reorder type animation
- The old reorder type is changed to ELM_GENGRID_REORDER_TYPE_SWAP.
- ELM_GENGRID_REORDER_TYPE_NORMAL is the default reorder type.

Test Plan:
1. elementary_test->"Gengrid Focus"
2. Enable "Reorder Mode Enable"
3. Move the items by keys

@feature

Reviewers: raster, seoz

CC: seoz, chinmaya061, aryarockstar
Differential Revision: https://phab.enlightenment.org/D813