Similar to TLS configuration that we can use on QNetworkRequest,
we can configure different options in our HTTP/2 handling by
providing QNetworkAccessManager with h2 configuration. Previously,
it was only possible internally in our auto-test - a hack with
QObject's properties and a private class. Now it's time to provide
a public API for this.
[ChangeLog][QtNetwork][QNetworkRequest] Add an ability to configure HTTP/2 protocol
Change-Id: I80266a74f6dcdfabb7fc05ed1dce17897bcda886
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>