Tested locally before & after change, and looked at code to compare.
Nothing seen or experienced that should affect things, from testing all
is working as expected with no difference from before.
- Update composer requirement of socialite to that which included slack.
- Updated PHP depds while there.
- Updated format of socialite events to align with current documentation
and to use class references instead of strings.
Added test and changed logic to properly check the view permissions for
the notification receiver before sending.
Required change to permissions applicator to allow the user to be
manually determined, and a service provider update to provide the class
as a singleton without a specific user, so it checks the current logged
in user on demand.
