Release v22.87.2

Fixed

• The frontend notEmpty rule now treats text as empty exactly when it contains only Unicode whitespace, the same set the backend uses, so a value such as U+0085 or U+FEFF is accepted or rejected identically on the client and the server. (#3224)
• An observable query whose arguments fail validation now delivers the validation results to the subscriber as an invalid query result and ends the subscription, over WebSocket and Server-Sent Events, in direct and hub mode, instead of a bare error message or a failed connection. Plain query requests and the React query hooks already surfaced these results. Controller-based observable queries over a direct WebSocket are tracked in #3230. (#3225)