efl_text_formatter: rename from Efl.Text.Formatter to Efl.Text_Formatter

this is needed in order to not collide with the Efl.Text Interface.
Theoretically eolian should have ordered on that, however, the checks
are buggy and only work out of tree.

ref T8648

Reviewed-by: Xavi Artigas <xavierartigas@yahoo.es>
Differential Revision: https://phab.enlightenment.org/D11662