efl_mono: add a free function to every owned type
this is another step towards enforcing free functions on every owned
type. To equip every owned type with a free function the following is
applied. Every owned ptr is assumed to be a heap pointer, with the free
function "free". Every string that is owed is converted to a mstring. a
pointer to a eo object is also assumed to be a heap pointer, and equiped
with the free function "free".
Differential Revision: https://phab.enlightenment.org/D7710