[➕ Feature]: Split between alert ingestion and workflow execution

[shahargl]

1. Currently, the workflow execution and alert ingestion are tightly coupled
2. This means it is hard to "restart" a workflow because currently, it means you need to trigger the alert again
3. It also uses insert_events which is "one to many" and can trigger other workflows

What we want to do:

1. Add "re-run workflow" without ingesting the alert again.
2. Similar to GitHub action restart workflow

Implementation (IMO)

1. Refactor WorkflowManager to have a clear interface
2. WorkflowManager should have restart_workflow(workflow_id, workflow_execution_id) that "knows" all the context from the workflow_execution_id so it can be restarted