ohos: Add qrc support

ArkWeb uses a native scheme handler: a custom scheme is registered on
the web kernel, and the handler callbacks then run on the web engine
IO thread for every request matching that scheme.

Register the "qrc" scheme and serve the embedded resources from the
handler using QResource. A missing resource is reported to the engine
with ERR_FILE_NOT_FOUND.

Because OH_ArkWeb_RegisterCustomSchemes() must run before
the web engine is initialized, it is called together with
WebviewController.initializeWebEngine() before the first Web component
is created. The handler is then bound to each WebView through its
webTag once the component exists.

Task-number: QTBUG-146838
Pick-to: 6.12
Change-Id: I5567cb4ffd3a5451bfed027e11bec91e9c5ce42b
Reviewed-by: Liang Qi <liang.qi@qt.io>
Reviewed-by: Zbigniew Chyla <zbigniew.chyla@qt.io>