Fix Undefined Min/Max Height in Inspector

[dennisadams]

Fixes #7672.
Following the terrain overhaul (#7061), the min/max height properties have moved from the QuadtreeTile's data to data.tileBoundingRegion and not all places were updated.
This PR updates the cesium inspector and also a couple of other places: Globe's getHeight and QuadtreePrimitive's updateHeights which share the relevant code.
Hope I haven't missed any others.

[cesium-concierge]

Thanks for the pull request @dennisadams!

• ❌ Missing CLA.
  • Please send in a Contributor License Agreement (CLA) and comment back here to let us know to check this!
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.
• ❔ Unit tests were not updated.
  • Make sure you've updated tests to reflect your changes, added tests for any new code, and ran the code coverage tool.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[kring]

Code looks good to me, thanks @dennisadams. Just needs a CHANGES.md update and confirmation the CLA has been signed.

[hpinkos]

No, I don't think we've received a CLA yet.

@dennisadams See https://github.com/AnalyticalGraphicsInc/cesium/blob/master/CONTRIBUTING.md#contributor-license-agreement-cla for instructions for sending over a contributor license agreement. Thanks!

[dennisadams]

I've just updated CHANGES.md and sent my CLA.
Thanks!

[pjcozzi]

Thanks again for the contribution, @dennisadams, we received your CLA.