Add typed timeout errors to the API and SDKs

A read query that runs past the 20 second limit is stopped and answered with a 408 timeout. Until now that status was missing from the API reference, so the SDKs reported it as an unknown error with nothing to catch.

• Added the 408 timeout to every read endpoint of the V2 API reference, with the message that tells you to narrow the date range or the filters and try again
• Added a typed timeout error to the Python and C# SDKs (ErrorTIMEOUT and RequestTimeoutException) so you can handle it without parsing the error text
• Documented the timeout in the REST API error table and in the SDK READMEs