KeyboardInterrupt handling

[tbenthompson]

Do something reasonable when adagrid job gets interrupted so that the job is likely to lose less data?

[tbenthompson]

signal handlers for event loop? is this supported on macos??

• https://docs.python.org/3.10/library/asyncio-eventloop.html#set-signal-handlers-for-sigint-and-sigterm
• https://stackoverflow.com/questions/54525836/where-do-i-catch-the-keyboardinterrupt-exception-in-this-async-setup/54528397#54528397