Define set of possible actions and way to reference values from previous states

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Actions must be able to map to an endpoint definition.
So, we must define the set of actions that are available, which corresponds with a method that is executed when that action's endpoint is called.

Example:
We can define an http-get, http-post or http-put action, etc, which can accept multiple action-params: a url, potentially with query params and a request-body; and these query params or request-body might depend on outputs from a previous state. So, on top of defining an initial set of possible actions, we also need a way to define action-params dynamically, perhaps referencing outputs or markets from previous states.