* DEV: Replace site_setting_saved DiscourseEvent with site_setting_changed
site_setting_saved is confusing for a few reasons:
- It is attached to the after_save of the ActiveRecord model. This is confusing because it only works 'properly' with the db_provider
- It passes the activerecord model as a parameter, which is confusing because you get access to the 'database' version of the setting, rather than the ruby setting. For example, booleans appear as 'y' or 'n' strings.
- When the event is called, the local process cache has not yet been updated. So if you call SiteSetting.setting_name inside the event handler, you will receive the old site setting value
I have deprecated that event, and added a new site_setting_changed event. It passes three parameters:
- Setting name (symbol)
- Old value (in ruby format)
- New value (in ruby format)
It is triggered after the setting has been persisted, and the local process cache has been updated.
This commit also includes a test case which describes the confusing behavior. This can be removed once site_setting_saved is removed.
Since Rails 5.2, the behavior of `attribute_changed?` inside `after_save` callbacks has changed, so we need to use `saved_change_to_attribute` instead. The site setting local_process_provider in test mode was covering up the issue.
If you turn it on now, default all users to approved since they were
previously. Also support approving a user that doesn't have a reviewable
record (it will be created first.)
This also includes a refactor to move class method calls to
`DiscourseEvent` into an initializer. Otherwise the load order of
classes makes a difference in the test environment and some settings
might be triggered and others not, randomly.
