[feat] Allow repo dispatch agent events to be passed an actor rather than assuming via what triggered the dispatch

I saw https://github.com/anthropics/claude-code-action/pull/826 was just merged recently, which broke one of my workflows while pointed at v1.

My workflow uses one workflow to listen for triggers using github actions events, and then creates a repository dispatch with a formatted prompt to the agent in another workflow. I'm using the peter-evans create dispatch action to create it, using the github actions token to create it.

While the intent of that PR was to prevent loops, I find the case of me manually triggering a repository dispatch to be quite rare. Additionally, users who were triggering those workflows via automation and getting into loops (I'm not positive if github actions' max recursion depth applies to repo dispatches or just workflow dispatches) will now also have broken workflows which they will remedy in the mean time by allowing bots back through, potentially re-introducing the usage issue.

It would be nice if (like bot_id and bot_name) we could specify the actor ID as inputs to the action (or in a known place where it can pull it from the client payload) so that even though an automation token triggers it, the actor is evaluated appropriately.