sdk-test-connect-disconnect Rust test

This module tests that we can observe connect/disconnect events for WebSocket connections.

Note: Also mirrored as a C# version at modules/sdk-test-connect-disconnect-cs, so must be kept in sync.

How to Run

Execute the tests on spacetimedb-sdk at test.rs:

# Will run both Rust/C# modules
cargo test -p spacetimedb-sdk connect