* feat(alerting): add optional email to ntfy provider
https://docs.ntfy.sh/publish/#e-mail-notifications
* feat(alerting): add optional click action to ntfy provider
https://docs.ntfy.sh/publish/#click-action
* feat(alerting): add option to disable firebase in ntfy provider
https://docs.ntfy.sh/publish/#disable-firebase
* feat(alerting): add option to disable message caching in ntfy provider
https://docs.ntfy.sh/publish/#message-caching
* test(alerting): add buildRequestBody tests for email and click properties
* test(alerting): add tests for Send to verify request headers
* feat(alerting): refactor to prefix firebase & cache with "disable"
This avoids the need for a pointer, as omitting these bools in the config defaults to false
and omitting to set these headers will use the server's default - which is enabled on ntfy.sh