Make xml of libraries editable

[TeaDrinkingProgrammer]

• [x] I agree to follow the Code of Conduct that this project adheres to.
• [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Is your feature request related to a problem? Please describe. Custom libraries are great. They allow people to easily expand the functionality of Draw.io. I am currently working on a custom library and there is a problem I constantly have: it is very cumbersome to make small changes to shapes. Let's say, for example, I want to change the text in a shape. I now have to put the shape in a drawio diagram, change the text, put it back in, delete the old shape and rename the new one. This gets very annoying after a few times and makes maintaining a custom shape libary more cumbersome than it needs to be.

Describe the solution you'd like I suggest making the deflated XML editable in the editor itself. This is already possible for individual shapes so it should be possible to implement. I came up with the idea after seeing this issue. This issue also discusses the issue but has been marked as stale and suggests a gui approach.

Describe alternatives you've considered I can also imagine people being able to double-click on a shape in the sidebar, opening a GUI and editing it that way but I think that would be time consuming to implement and I would be happy with any solution at the moment.

Additional context I do not know if this is the best solution so any other ideas are welcome. The main issue is improving editability of custom shape libraries