* EXreaction/ticket/11415:
[ticket/11415] Add test for find_from_extension()
[ticket/11415] Send the extension base the finder rather than the manager
[ticket/11415] Create function in finder find_from_extension
[ticket/11415] Fix ext.manager constructor in tests
[ticket/11415] Make migrator/ext.manager dependencies of the base ext class
[ticket/11415] Remove migrator dependency from extension manager
[ticket/11415] Move migrator to base extension class from ext.manager
[ticket/11415] Move while loop from ext manager to acp_extensions.php
This will now also enable us to test the $use_all_available parameter of
get_module_infos(), which will not only return the module infos for enabled
extensions but also those from disabled extensions.
PHPBB3-11465
Remove dependency of extension manager for migrator.
Keeping load_migrations function for others to use if they desire
but requiring the finder be sent to it in order to use it.
PHPBB3-11386
The enable or purge operation of an extension could take a long time if an
expensive operation needs to be executed on a large set of data. To allow
this to succeed from a web interface with max_execution_time set in the
webserver's php configuration, subsequent requests must continue the
operation started earlier. So individual enable and purge implementations
must be able to spread their work across multiple steps.
PHPBB3-10323
