Enhancement: Add filtering option to treeview

[TonyGravagno]

It would help if we could do a quick search for props within an object.

You can see this feature implemented in another similar project: TypeScript Explorer

One difference that I'd like to see is the ability to show Only the props that match a specific filter. In the example we see the existing tree is modified with styling. That's good for some purposes, but for others it helps to just see what we want at that moment.

Also note that when filtering for 'onclick' that implementation shows "on" and "click" as well as "onclick". While that could be helpful in rare circumstances I find that to be annoyingly too (non)intuitive. YMMV

You might be able to incorporate the FOSS from that project (with proper attribution of course) as a starting point for this enhancement, or even as-is as just the first version of this feature.

Thanks!