feat: support parallel calls

[andreitava-uip]

Support for multiple tool calls of the same tool.

• this is only possible via the SendAPI
• keeping the conditional router edge and doing the logic there maintains the diagram visualization
• ToolNode was updated to accept direct tool calls via a new custom model (which also needs to contain the state for the wrappers)
  • ToolNode still supports getting the state directly as well
• added extra: "allow" to AgentGraphState and used it where we needed the dynamic CompleteAgentGraphState
  • surprisingly, does not work if we annotate the state with it for a node, extra fields will be lost.

WIP:
Guardrails are broken, Guardrails subgraph must also handle input via send