Builtin plugins (#3889)

* Allow loading of "builtin" plugins, even if "plugins" are not explicitly loaded

* Updates for 'admin' buttons:

- Make them work like proper links
- Hidden if 'hide_admin_link' customization option is set
- Check for user staff status

* Cleanup rendering of "plugins" display

* Consolidate InvenTree barcode plugins into single plugin class

* Hide "install plugin" button if plugins are not enabled

* Add info message is external plugins are not enabled

* Fixes for loading plugins

- Always load 'builtin' plugins
- Refactor calls to "is_active" at various points in codebase

* Various tweaks

- Improve builtin plugin descriptions
- Spelling fixes

* Adjust plugin detail for builtin plugins

* Simplify barcode plugin class

* Simplify template rendering

* Bug fix for inventree barcode plugin

* Revert "Simplify template rendering"

This reverts commit 3a6755a659.

* Re-re-improve template rendering

- Required as the template has been refactored for both "active" and "inactive" plugins

* Fixing unit tests for barcode plugin

* Ensure that barcode scan actions do not take a "long time":

- Add a default timeout of 0.1s to any POST or GET request in the testing framework
- Can be overridden by calling method if desired

* Display plugin "builtin" status in admin panel

* Fix unit tests for plugin API

* Further unit testing fixes

* Version number tweaks

* Further tweaks for unit testing

* Allow longer timeout for report printing via API

* Increase default timeout for API tests

- Sometimes CPU spike can cause the test to fail :|

* label printing can take a bit longer

* Remove timeout requirement from API tester

- Too variable to be reliable for CI

InvenTree/plugin/apps.py

@@ -7,7 +7,6 @@ The main code for plugin special sauce is in the plugin registry in `InvenTree/p
 import logging
 
 from django.apps import AppConfig
-from django.conf import settings
 from django.utils.translation import gettext_lazy as _
 
 from maintenance_mode.core import set_maintenance_mode
@@ -26,34 +25,34 @@ class PluginAppConfig(AppConfig):
 
     def ready(self):
         """The ready method is extended to initialize plugins."""
-        if settings.PLUGINS_ENABLED:
-            if not canAppAccessDatabase(allow_test=True, allow_plugins=True):
-                logger.info("Skipping plugin loading sequence")  # pragma: no cover
-            else:
-                logger.info('Loading InvenTree plugins')
+        if not canAppAccessDatabase(allow_test=True, allow_plugins=True):
+            logger.info("Skipping plugin loading sequence")  # pragma: no cover
+        else:
+            logger.info('Loading InvenTree plugins')
 
-                if not registry.is_loading:
-                    # this is the first startup
-                    try:
-                        from common.models import InvenTreeSetting
-                        if InvenTreeSetting.get_setting('PLUGIN_ON_STARTUP', create=False, cache=False):
-                            # make sure all plugins are installed
-                            registry.install_plugin_file()
-                    except Exception:  # pragma: no cover
-                        pass
+            if not registry.is_loading:
+                # this is the first startup
+                try:
+                    from common.models import InvenTreeSetting
+                    if InvenTreeSetting.get_setting('PLUGIN_ON_STARTUP', create=False, cache=False):
+                        # make sure all plugins are installed
+                        registry.install_plugin_file()
+                except Exception:  # pragma: no cover
+                    pass
 
-                    # get plugins and init them
-                    registry.plugin_modules = registry.collect_plugins()
-                    registry.load_plugins()
+                # get plugins and init them
+                registry.plugin_modules = registry.collect_plugins()
+                registry.load_plugins()
 
-                    # drop out of maintenance
-                    # makes sure we did not have an error in reloading and maintenance is still active
-                    set_maintenance_mode(False)
+                # drop out of maintenance
+                # makes sure we did not have an error in reloading and maintenance is still active
+                set_maintenance_mode(False)
 
-            # check git version
-            registry.git_is_modern = check_git_version()
-            if not registry.git_is_modern:  # pragma: no cover  # simulating old git seems not worth it for coverage
-                log_error(_('Your enviroment has an outdated git version. This prevents InvenTree from loading plugin details.'), 'load')
+        # check git version
+        registry.git_is_modern = check_git_version()
+
+        if not registry.git_is_modern:  # pragma: no cover  # simulating old git seems not worth it for coverage
+            log_error(_('Your environment has an outdated git version. This prevents InvenTree from loading plugin details.'), 'load')
 
         else:
             logger.info("Plugins not enabled - skipping loading sequence")  # pragma: no cover