Sandbox Service

[verdverm]

Sandboxes are important, iykyk, ADK should have a service like it does for sessions.

I have one here: https://github.com/hofstadter-io/hof/tree/_next/lib/agent/services/environ

1. It is not integrated into ADK, it is highly interwoven in my code
2. It needs good integration with Session, not necessarily direct, i.e. both need to be involved in a write_file tool call
3. The example is also integrated with my time travel extension to ADK SessionService
4. There is a simpler version where you set the sandbox at the start, and don't track changes, but I already have change tracking and don't want to give that up
5. OCI is an excellent choice for a default implementation

Opened a related discussion in: google/adk-python#4631