Regarding function naming

@microsoft/signalr 10.0.0

Regarding the naming of callback functions, will camelCase be adopted in the future? It looks strange now. For example, changing 'onreconnecting' to 'onReconnecting' and 'onreconnected' to 'onReconnected' and 'onclose' to 'onClose', my cspell plugin also prompts me:

[https://github.com/dotnet/aspnetcore/blob/eec80e1c63963802a215d58b3907d6e46090fc28/src/SignalR/clients/ts/signalr/src/HubConnection.ts#L570`onclose`](https://github.com/dotnet/aspnetcore/blob/eec80e1c63963802a215d58b3907d6e46090fc28/src/SignalR/clients/ts/signalr/src/HubConnection.ts#L570%60onclose%60)

Start with src/SignalR/clients/ts/signalr/src/HubConnection.ts at the referenced line and inspect the onclose, onreconnecting, and onreconnected callback API. Review how these names are exposed and whether changing them would affect compatibility; done would require a decided naming direction and the associated API and test updates.

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