Make modmatrix accessible from new Reddit

[eritbh]

Would probably make sense to move it to the sub context menu and present it in a window.

[creesch]

Since an entire rewrite isn't really feasible in the short term (considering our available dev fte) the easiest way is likely to load the old reddit modlog in an iframe which gives access to modmatrix at the same time.

If we don't want to show the log itself we could make it so the matrix opens by default.

Edit:

I should clarify, we can't simply copy the logic into an overlay as the current implementation really follows a different code pattern compared to the rest of toolbox. Technically we could just use this but it would be cleaner to do a rewrite/refactor.

There are also some issues with the current implementation that would need to be addressed anyway.