[core] When address is already in use, local server blocks with swift task continuation misused

[sebsto]

Steps to reproduce:

• Start the local server for one of the examples
• From another terminal, start another local server.

Current behavior:
The second server blocks with message SWIFT TASK CONTINUATION MISUSE: withLocalServer(invocationEndpoint:_:) leaked its continuation!

Desired behavior:
Local server fails to start with an error like bind(descriptor:ptr:bytes:): Address already in use (errno: 48)

Root cause:
This block of code must be wrapped into a do catch block and call continuation.resume(throwing: error) when an error is throw.