fix looker3d controls styles in light theme

[imanjra]

What changes are proposed in this pull request?

Improve Looker3D controls styles to make it consistent with looker 2D controls styles

How is this patch tested? If it is not, please explain why.

Tested visually in both light and dark theme

Release Notes

Is this a user-facing change that should be mentioned in the release notes?

• No. You can skip the rest of this section.
• Yes. Give a description of this change to be included in the release
  notes for FiftyOne users.

(Details in 1-2 sentences. You can just refer to another PR with a description
if this PR is part of a larger change.)

What areas of FiftyOne does this PR affect?

• App: FiftyOne application changes
• Build: Build and test infrastructure changes
• Core: Core fiftyone Python library changes
• Documentation: FiftyOne documentation changes
• Other

[benjaminpkane]

Looks good. For consistency, can the grey border be removed from the Looker3d controls row? It also looks like the the icons are smaller in Looker3d. And there is no animation on hover, but that is a smaller detail.

[brimoor]

@imanjra can you address these related items before merging?

1. Clicking the ? icon in Looker3D a second time does not close the help menu (it immediately reopens)

2. This Looker3D component needs to respect light theme

3. The close modal buttons are inconsistent in light theme (I think dark color makes sense)

4. This overlay text should be white in both dark and light theme:

5. Remove shadow from Looker3D's toolbar for consistency with Looker2D's toolbar:

6. Use same darker background for JSON viewer that is used in help menu (too difficult to read the JSON viewer currently). Also I think the transparency is too much right now. Better to make it more opaque so the modal text is easier to read:

[brimoor]

LGTM, thank you @imanjra!