Web Viewer UI Improvements

[kwokcb]

Changes

• Add FPS timer. Toggles via T / t(imer). ( SHIFT-f / F already used for frame-grab so don't want to mix things up ).
• Make UI consistent for font, and color
• Make menus not be file names but try and parse out useful words. Remove extensions.
• Prevent UI from overlapping and wrapping when page is narrow (mobile and desktop).

Results

Material labels	Geometry labels

With background	Without background

• UI overlap guards

Mobile	Desktop
Avoid labels + menu items from wrapping and overwriting each other when narrow. Isn't really responsive but don't want to change current fixed formatting. (e.g. iPhone 12 Pro Sim)
Prevent property editor / menu overlapping as much as possible

[kwokcb]

@jstone-lucasfilm , this is mostly style sheets and text formatting. The FPS is a small change to give some rudimentary performance number. Some shaders are very slow (separate issue) but relative perf can be given as a number at least.

[jstone-lucasfilm]

This looks like a worthwhile improvement, thanks @kwokcb!