CSS styles can contain '@media <rule> {...}' blocks, which were
previously ignored for all values except "screen".
To use a media rule other than the default "screen" rule,
specify it before calling setHtml() with setMetaInformation()
and the new info value 'CssMedia'.
[ChangeLog][Gui][QTextDocument] Add css media rule support
for QTextDocument::setHtml()
Pick-to: 6.3
Fixes: QTBUG-98408
Change-Id: Ie05f815a6dedbd970210f467e26b116f6ee3b9ca
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>