Add an ability for plugins to listening to real-time processing of "skipped" scenarios

[nvborisenko]

Is your feature request related to a problem? Please describe.
I am creating a plugin for gauge, which is listening to execution events via grpc.

Describe the solution you'd like
All skipped scenarios/specs should be reported to plugins in real-time.

Describe alternatives you've considered
?

Additional context
reportportal/agent-net-gauge#53