Ensures some sensible text is always in webhook text data.
Also aligned some notification reporting to use centralised activity
system instead of custom success events.
For #4216
This is to encourge the ":count" values to be used instead of 1s in the
translated variants so that non-pluralised languages are hardcoded with
"1"s in their content, even when not used in a singular context.
For #4040
Altered & updated permissions repo, and existing connected
RoleController to suit.
Also extracts in-app success notifications to auto activity system.
Tweaked tests where required.
