Add ActionExecutionPolicy

[qreshi]

Issue #, if available:

Description of changes:

• Adds an ActionExecutionPolicy data model that can be used during Aggregation Monitor execution to control Action execution behavior
• Updates MonitorRunner to use ActionExecutionPolicy (although the MonitorRunner logic is still partially incomplete, it's missing things like updating Alerts with action execution run results, etc.)
• Minor formatting changes

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[qreshi]

Rebased with the head of the dev branch and updated the PR to integrate with the changes. The MonitorRunner for Aggregation Monitor is now functional in generating new alerts and deduping but there are still some things missing:

• Input results and trigger results are empty from monitor execution response
  • This was seen with composite aggregation so what's probably happening is the after_key is present and being used but the next page is empty since all the results were shown on the first page (leading to an empty run in the do-while loop of the runner)
• Alerts are being indexed before they are put in the action context but the Alerts in memory are not being updated with their ID after indexing so new alerts don't have the IDs present in the action context
• triggerResults needs to be continually appended to across the do-while iterations so it is complete by the end of the run (for not it is just reset each iteration)
• Alerts need to be updated with the actionRunResults and reindexed/updated at the end of the run
• PER_EXECUTION actions need to be lifted out of the do-while since the Actions should not be executed once per iteration of the do-while loop but instead be done once per execution
  • In this case the Alerts might just need to be added up so the Actions with PER_EXECUTION have them all loaded into the action context for execution

There are also things like missing circuit breakers and integration tests but the above was mostly to capture bugs/misbehaving functionality.

[qreshi]

Merging in now as the changes were discussed with @rishabhmaurya