Use reccomened gui_hooks for playAudio JS bridge to avoid affecting other addons

[jamesrwaugh]

Resolves #92

Hi,

I'm developing an Anki addon and I found how Migaku is "hijacking" the private AnkiWebView _onBridgeCmd prevents a JS callback from being called when handing a pycmd on new webviews.

The real issue is that prevBridgeReroute in main.py should have a return statement on the last line, like this, so the results can be passed to a JavaScript callback.

def prevBridgeReroute(self, cmd):
    if cmd.startswith('playAudio;'):
        if checkProfile() and getConfig()['PlayAudioOnClick'] == 'on':
            clickPlayAudio(cmd)
            return
    else:
        return ogAnkiWebBridge(self, cmd)

But, the docs recommended using gui_hooks.webview_did_receive_js_message here which I think is the cleaner choice. When I make this change, it resolves the issue. Did a test on my Linux machine and the on-click audio still works as expected.
https://addon-docs.ankiweb.net/#/hooks-and-filters?id=webview

webview.py in Anki also discourages setting _onBridgeCmd and onBridgeCmd manually:

# in new code, use .set_bridge_command() instead of setting this directly
self.onBridgeCmd: Callable[[str], Any] = self.defaultOnBridgeCmd

I'd be happy to make a small addon to show further reproduction steps if needed.