This patch adds support for get lookups of QVariantMap properties.
Setting or modifying is not supported and will reject.
Also, QQmlJSRegisterContent::JavaScriptObjectProperty was
renamed to QQmlJSRegisterContent::GenericObjectProperty
Tests were added to TestQmllint::cleanQmlCode() and
tst_QmlCppCodegen::variantMapLookup().
Pick-to: 6.5
Fixes: QTBUG-105545
Change-Id: I653ee4e7de1fb1514e1e563a92cfc28633268a7e
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Olivier De Cannière