Pending action support in multiple actions

[curtisman]

If an action requires the content of the result from previous action, multiple action will generate a pending request entry.
The pending request entry is converted into a "PendingRequestAction", and during execute, the request will be translated again with the current history context.

• A lot of the diff is from breaking apart the file requestCommandHandler.ts
• executeActions is not a queue to allow pending request action to be expanded to more actions.
• streaming now allow different actionIndex as the streaming target so that translation for pending request can be streamed too, but if the translation is not a multiple action.
• Add toggles for result id and pending for multiple actions.