efl_mono: Move event generators to its own header.

efl_mono: Move event generators to its own header.

Summary:
Making it easier to share code between self and inherited events.

During this move, the namespace and keyword headers were merged into the
name_helpers header.

Also added the first seed of a generic namespace reducer function,
to be used by other functions in later commits.
Depends on D5994

Reviewers: felipealmeida

Reviewed By: felipealmeida

Subscribers: segfaultxavi, cedric

Differential Revision: https://phab.enlightenment.org/D5995