ping() rejects immediately in non-connected states instead of deferring (RTN13d)

[paddybyers]

Spec point

• RTN13d: "If the connection is not in the CONNECTED state when ping() is called, the ping is deferred until the connection reaches a state that can resolve it (CONNECTED, FAILED, CLOSED, SUSPENDED)."

Observed behaviour

`ping()` immediately rejects with "not connected" when called in CONNECTING or DISCONNECTED state. There is no deferral mechanism. `ConnectionManager.ping()` checks `this.state.state !== 'connected'` and throws immediately.

Test

This deviation is documented in the Realtime UTS test suite. The adapted tests assert immediate rejection instead of deferral.

Note: This deviation is from the Realtime test suite (not REST), so there is no `RUN_DEVIATIONS` reproduction command in the current REST PR. The test is documented in `test/uts/deviations.md`.

From PR #2191, branch `uts-rest`.

┆Issue is synchronized with this Jira Task by Unito