feat: conversational agent support

[mike-deem-uipath]

Depends on UiPath/uipath-runtime-python#65

Adds support for conversational agents:

• Adds some optional overrides for local testing with CAS (configured using env vars)
• Log conversation error events received from CAS over the websocket bridge
• Adds an is_conversational getter to AgentDefinition
• Adds --keep-state-file cli option that causes the state.db to be preserved. This allows conversational agent runs to accumulate conversation history.

Also

• Fixed a minor typo in the autonomous agent system prompt.