Stream output of a user project with serve

[tcdent]

• Shared logic for running user projects between serve and cli
• Added a new log method log.stream which can be appended to (doesn't insert newlines).
• Added a new log handler for streaming log information to other parts of the app (preserves existing stdout/stderr)
• Allows custom framework to be executed but not modified.
• Verify POST /process & callbacks
• Is messy; cleanup serve.py
• type checking
• Docker needs more work

Currently testing this inside a project dir with: python ../AgentStack/agentstack/serve/serve.py