This PR adds potentially stale events as available to all addons and
adds a formatted message.
## Discussion
I'd still be interested in hearing input on whether the event type
should be selectable by addons or not before we start emitting the
event. I'm leaning towards "yes", but I'll take your thoughts into
consideration.
###What
Adds an optional sensitive parameter for customHeaders to all current
addons. It is sensitive because the user might be including api key headers.
* feat: add new more specific feature/environment events to addons
* Updated strategy change text
* Update all three addon messages for strategy
* Link to new features view for strategy change text
Co-authored-by: Ivar Conradi Østhus <ivarconr@gmail.com>
