Add "run now" button to the Rules and Connectors UI

[mcpate]

Describe the feature:
It would be fantastic to have a button on the Rule and Connectors UI ("Rules" tab) that allows running a rule add hoc.

Describe a specific use case for the feature:
A user has a Rule that is active, they make a change to the Rule that should cause it to no longer be active, but the Rule doesn't run again for several hours. Unless they modify the frequency, test it, then set the frequency back to what it was, they have to remember to come back to the Rule once it naturally runs again to make sure it is no longer active. If there was some sort of a "run now" button, it would allow much faster ad hoc testing/running of a Rule.

This could also be useful if a Rule runs infrequently, and was Active last time it ran, but before the user investigates further they want to run it ad hoc to verify if it is still active.

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)

[mikecote]

Closing in favour of #50215.