Better error message when SignalR message size limit exceeded

[SteveSandersonMS]

Currently when you have an event or JS interop call whose payload exceeds the SignalR message size limit, the circuit disconnects (which is correct) but the error message is unhelpful:

Connection disconnected with error 'Error: Server returned an error on close: Connection closed with an error.'

(Source)

As part of #30289 we plan to create convenient new APIs to transmit large amounts of data without exceeding message limits, but it will still be possible to exceed the message size limits if you choose not to use those new APIs.

We should ideally:

• On startup, detect the configured SignalR max message size
• Supply this info to the JS side (e.g., in the options we transmit anyway)
• Have the JS-side code specifically catch cases where you're doing an event or JS interop call that's too big, and fail it before it even gets sent (still causing a circuit disconnect) but with a much clearer message that points to docs

The docs will explain the new APIs that you should use when sending large amounts of data. We will not recommend increasing the SignalR message size, as that isn't a real solution (maybe you still need even bigger payloads later).

[ghost]

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We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
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[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.