Some names have not been changed, hopefully making a distinction
between legacy APIs and internal code (elm_layout_blah) and valid EO
usages.
This means many internal functions are still elm_layout_ as their
sole purpose is to support the legacy API.
Ref T5315
The expected usage is efl_text_set(efl_part(layout, part), text);
Same for text_get.
Also, added an example how to make API easier with providing
efl_text_set/get for the widget itself, in efl_ui_button. Please see
this example.