Streamable HTTP - resume streams on disconnect

[ihrpr]

As per spec servers might support resumability and redelivery.

Introducing resumability and re-delivery of events for disconnection within the same client.

• maintaining a map of streamID per request
• moved a special case for standalone stream to a map for simplicity
• adding StreamableHTTPReconnectionOptions interface for custom reconnection and backoff
• adding example of start-notification-stream' tool which starts notifications for that can be used for testing

Follow ups:

• resume long running requests from a new instance of the client

[jspahrsummers]

Haven't had a chance to look at the examples or tests in depth yet, but pointed out some things I think we need to change before getting this in.

[jspahrsummers]

There's probably a library on npm that can do some of this out of the box.

[ihrpr]

the logic is minimal, can come back to this later if it's non-blocking?

[jspahrsummers]

I don't have bandwidth to review the tests and examples, but the main implementation looks good to me now.