Add changes result to Github Action output

[arxeiss]

Is your feature request related to a problem? Please describe.

After the Github Application deprecation (#2648 ) I need to write custom Github workflow to send result to Slack. However, current Github Action does not allow that, because is not exposing the result - only total amount of changes.

Describe the solution you'd like

I would like to add changes to the action output, so next step in workflow could use that.

Describe alternatives you've considered

Implementing Slack notification into Github Action.