[BUG] Multimedia sent to a GoldenLayout pane with 'replace' update method doesn't replace existing content

[nyweryl]

Describe the bug

When sending multimedia elements to a GoldenLayout webclient pane they always get appended to existing content, even if the update method of the pane is defined as "replace".

To Reproduce

Steps to reproduce the behavior:

1. Define a new GoldenLayout pane, with the updateMethod of the componentState set to replace, for example:

   type: 'component',
   componentName: 'evennia',
   componentId: 'evennia',
   title: 'Minimap',
   isClosable: false,
   componentState: {
       types: 'minimap',
       updateMethod: 'replace',
   },
}

2. Create a piece of code that sends a message with multimedia content to that pane, for example:

obj.msg(image=("https://avatars.githubusercontent.com/u/23739149", {"type": "minimap"}))

3. Make sure that piece fires multiple times.
4. See the result:
   

Expected behavior

I expect the existing contents of the pane to be completely replaced by the multimedia content.

Environment, Evennia version, OS etc

     Evennia version: 2.2.0 (rev 8593c7eb41)
     OS: posix
     Python: 3.11.1
     Twisted: 22.10.0
     Django: 4.1.3

Additional context

As a work-around I added a few lines to the multimedia plugin:

let multimedia_plugin = (function () {
    //
    var image = function (args, kwargs) {
        let options = window.options;
        if( !("mm_image" in options) || options["mm_image"] === false ) { return; }

        var mwins = window.plugins["goldenlayout"].routeMessage(args, kwargs);
        mwins.forEach( function (mwin) {
            // Lyrewyn
            // Check the defined updatemethod for the appropiate action.
            let updateMethod = mwin.attr("updateMethod");
            if ( updateMethod === "replace" ) {
                mwin.html("<img src='"+ args[0] +"'/>");    
            } else {
                mwin.append("<img src='"+ args[0] +"'/>");
            }
            //
            mwin.scrollTop(mwin[0].scrollHeight);
        });
    }

[Chetral]

Another, easier, work-around is to send an empty message of type "text" with the same tag before the new image (or message you want to show)

obj.msg(text=(' ', {"type": "minimap"}), options=None)

The message type "text" actually reset the goldenlayout component.