[DnD] Fix bug of hard-coded type when drag
[DnD] Fix bug of hard-coded type when drag

Summary:
When we start dragging, the type is always set to "text/uri-list" no matter the format type set by application.
This patch fixs this hard-coded type issue. It will set types corresponding to the format type set by application.
For example, if application set format as ELM_SEL_FORMAT_TEXT, it will set types UTF8_STRING, STRING, COMPOUND_TEXT, TEXT,
text/plain, text/plain;charset=utf-8.

Reviewers: JackDanielZ, raster

Reviewed By: raster

CC: woohyun, seoz

Differential Revision: https://phab.enlightenment.org/D546

tasn/elementary,tasn/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,tasn/elementary