wasm: a11y - Add call to setActive

There are various tests for this within the accessibility system.
Without it, it is not consistent what works and what does not work.

Task-number: QTBUG-134657
Change-Id: Idfa8905f377e2ef00a4d1af26cbf001064bc75dc
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/wasm/qwasmaccessibility.cpp

@@ -88,6 +88,7 @@ void QWasmAccessibility::enableAccessibility()
 
     Q_ASSERT(!m_accessibilityEnabled);
     m_accessibilityEnabled = true;
+    setActive(true);
     for (const auto& [key, value] : m_enableButtons) {
         const auto &[element, callback] = value;
         Q_UNUSED(key);