Virtualize the Icon Browser list

[joebochill]

Describe the desired behavior

The IconBrowser page should only render enough icons to fill the screen at one time.

Describe the current behavior

Right now all of the icons are rendered (>2000) and it causes poor performance on the Icon Browser page

Is this request related to a current issue?

Performance issues

Additional Context

There should be a number of third party libraries (or something in MUI) that we can use to do this.

[huayunh]

(This might be a MUI v5 thing; the existing docit icons page loads within a tolerable time)

[joebochill]

Yes, this is post-MUI5 conversion. The number of icons (DOM nodes) on the page has nearly doubled with the addition of the new icons.