New features

Update to XMLHttpRequest version "15 August 2022".
Added support for automatic progress events in MockXhrServer via the progressRate field.
The MockXhrServer now automatically sets the Content-Length response header for object request handlers.
setResponseBody() now automatically sets the Content-Length response header if setResponseHeaders() was not called.

Bug fixes

Added missing validation in open() that throws an exception if the method argument is not a method.
Distinguish between when the async argument is omitted and when it's undefined in open().
On a readystatechange event, the listener list was not cloned prior to calling the event listeners.
Added missing header name and value validation in setRequestHeader().
Added the Content-Type request header when the request body is a FormData.
Don't discard empty header values given to setRequestHeader().