eolian_mono: parse `binbuf` and `event` keywords, also re-enable binbuf tests

eolian_mono: parse `binbuf` and `event` keywords, also re-enable binbuf tests

Summary:
Parse `binbuf` and `event` type names and generate the proper binding type.

In 288f645e3cdb tests for `Eina.Binbuf` were disabled in order to avoid the
usage of deprecated notations in eolian.

Since the new `binbuf` keyword works as a substitute for the old notation
`ptr(Eina.Binbuf)`, tests were updated and re-enabled using the new notation.

Test Plan: `meson test`

Reviewers: felipealmeida, lauromoura, q66

Reviewed By: q66

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9349