Gracefully stop the functions host and propagate cancellation tokens

### Description

Allow users to stop or terminate the function app. This action should trigger a cancellation token, similar to how it works in production when the platform shuts down a host instance, ensuring the token is propagated to the language workers. Pressing **Ctrl + C** is one such signal that terminates the process. Additionally, investigate termination signals across different operating systems, such as macOS.

Start by tracing how the functions host handles Ctrl+C and other termination signals, then follow how cancellation is propagated to language workers. Compare behavior across the operating systems mentioned in the issue. Done means users can stop the local function app gracefully and workers receive the cancellation token consistently.

Written by the indexing model from the issue text.