Editor: Initial implementation of TabbedPanel element

[sdinesh86]

As per the discussion in PR #17443 will be implementing a few things for the editor. this is a the first of many PR's.

This PR adds a tabbed panel in the UI.
I have sort of just moved the logic from the Sidebar.js to a new UI element and added few more methods.

Next I will be replacing the current tabbed panels with this implementation.

[mrdoob]

Any chance you could add a screenshot of how does this look like?

[sdinesh86]

EDIT here is the link to sidebar
https://raw.githack.com/sdinesh86/three.js/editor-ui-additions/editor/index.html

So it looks the same its just that the code is different i will push the changes on sidebar update the PR

[mrdoob]

Oh I see.

Next I will be replacing the current tabbed panels with this implementation.

Can you make these changes as part of this PR too?

[sdinesh86]

I will make the changes on the Properties panel as well and update it

[sdinesh86]

done you can check it

[mrdoob]

Looking good!

[mrdoob]

I think UI.TabbedPanel.prototype.addTab would be a better name here.

[sdinesh86]

I initiallt thought of that name, but now i dont remember why i changed it :(

[mrdoob]

Thanks got changing the name. I think you forgot to update all the calls.

[sdinesh86]

OOPS

[mrdoob]

Thanks!