Editor menu customization

I can easily change the "Help" menu and add my own link to it using editor themes .
Same way is there a documentation which explains how to add a new menu to editor and add an action to that?

It is not something we've formally exposed. There are apis under the covers to do it, but I'm not sure if it gives the flexibility it should and can be quite awkward to work with depending on the actual requirements.

Can you explain a bit more about what you're trying to do?

What I am trying is create a menu which can fire system command in backend .
For example get the old flow from backup/s3 and update existing .