Add critical ems "callhome.data.outage.detected" to ems.yaml

[ranganetapp]

Is your feature request related to a problem? Please describe.
"callhome.data.outage.detected" ems is introduced from 9.17.1, this will help to detect when multiple nodes goes down.

Describe the solution you'd like

Add below ems in https://github.com/NetApp/harvest/blob/main/conf/ems/9.6.0/ems.yaml

=======

• name: callhome.data.outage.detected
  exports:
  • ^^node.name => node
  • parameters.subject => subject
    =========
    Describe alternatives you've considered
    May be a local ems.yaml file independent from harvest image

Additional context
We are using harvest to monitor ANF fleet, this ems helps TTD any data plane outages.

[rahulguptajss]

@ranganetapp This ems has been added to nightly build. If you want to try it out. Thanks.