chart2, sfx2: only load one document per test

Add UnoApiTest::disposeAndLoadFromURL for tests where
we need to close the current document and open a new one

Change-Id: Ia9419d0743f4a1c22d8c4d8b91bc168cd43533d2
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/198966
Tested-by: Jenkins
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

test/source/unoapi_test.cxx

@@ -286,6 +286,12 @@ void UnoApiTest::loadFromURL(OUString const& rURL, const char* pPassword)
     }
 }
 
+void UnoApiTest::dispose()
+{
+    mxComponent->dispose();
+    mxComponent.clear();
+}
+
 void UnoApiTest::loadWithParams(OUString const& rURL,
                                 const uno::Sequence<beans::PropertyValue>& rParams)
 {