Organizer-level plugins (#5305)

* Add version notes to the docs

* Adapt signal handling

* Add UI

* Add API

* API and tests

* Fix registry

* Update doc/development/api/plugins.rst

Co-authored-by: Felix Rindt <felix@rindt.me>

* Fix failing tests

* Apply suggestions from code review

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Update src/pretix/control/templates/pretixcontrol/organizers/plugin_events.html

Co-authored-by: luelista <weller@rami.io>

* Update src/pretix/control/templates/pretixcontrol/organizers/plugins.html

Co-authored-by: luelista <weller@rami.io>

* Update src/pretix/control/templates/pretixcontrol/organizers/plugins.html

Co-authored-by: luelista <weller@rami.io>

* Update src/pretix/control/navigation.py

Co-authored-by: luelista <weller@rami.io>

* Update src/pretix/control/urls.py

Co-authored-by: luelista <weller@rami.io>

* Apply suggestion from @wiffbi

* REbase migration

* Fix review note

* Fix test cases

* Remove plugin from all events if disabled on org level

* Update doc/development/api/plugins.rst

* Unify registries

* Rebase migration

---------

Co-authored-by: Felix Rindt <felix@rindt.me>
Co-authored-by: Richard Schreiber <schreiber@rami.io>
Co-authored-by: luelista <weller@rami.io>

src/pretix/settings.py

@@ -217,6 +217,8 @@ if config.getboolean('pretix', 'trust_x_forwarded_proto', fallback=False):
 
 PRETIX_PLUGINS_DEFAULT = config.get('pretix', 'plugins_default',
                                     fallback='pretix.plugins.sendmail,pretix.plugins.statistics,pretix.plugins.checkinlists')
+PRETIX_PLUGINS_ORGANIZER_DEFAULT = config.get('pretix', 'plugins_organizer_default',
+                                              fallback='')
 PRETIX_PLUGINS_EXCLUDE = config.get('pretix', 'plugins_exclude', fallback='').split(',')
 PRETIX_PLUGINS_SHOW_META = config.getboolean('pretix', 'plugins_show_meta', fallback=True)