Add export option to drop user security definers from views

[Cruiser13]

Steps to reproduce

1. Export a database with views
2. The dump will have lines like this:

DROP TABLE IF EXISTS object_2;
CREATE ALGORITHM=UNDEFINED DEFINER=someuser@localhost SQL SECURITY DEFINER VIEW object_2 AS select object_query_2.oo_id AS oo_id,...

3. If you import the dump on another server (with a different username) with phpmyadmin, the views will be useless because the user there has no permission for the views.

Expected behaviour

Click some checkbox or option to export views without the definition of the current user of this view so it can be properly reimported by phpmyadmin.

Actual behaviour

Currently you'll have to manually edit each dump and remove the security definition before reimporting it on another server which is error prone and ressource intensive on large MySQL dumps.