Fixed pixel size for polylines and point clouds under different resolutions

[IanLilleyT]

This is a partial fix for #8113

Polylines and point clouds had a number of areas that were not consistently sized between different resolutions:

• Point cloud size
• Styled point cloud size
• Point cloud eye dome lighting radius
• Polyline arrow
• Polyline dash
• Polyline shadow volume

Point cloud
new (low res):

new (high res):

cesium 1.60 (low res):

Polylines
new (low res):

new (high res):

cesium 1.60 (low res):

Further thoughts:

• I tried to move the pixel ratio multiply outside shaders where possible, but some systems are not flexible enough for this. See PolylineShadowVolumeMorphVS.glsl, which "spawns" the czm_batchTable_width function prior to shader compilation, where there is no easy way to insert the pixel ratio multiply. getPointSizeFromStyle in PointCloud.js has the same problem.
• Polylines which use the renderState's lineWidth property still look incorrect. This is because they are rendered as GL lines which is capped to 1 pixel on many computers. Example below:

Native resolution:

Browser recommended resolution:

[cesium-concierge]

Thanks for the pull request @IanLilleyT!

• ✔️ Signed CLA found.
• ❔ 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.

[mramato]

Tagged this for next release since I think it's important to get out and is a regression, @lilleyse I assume you'll be able to review/merge this today?

[lilleyse]

@mramato Yes I'll review today

[lilleyse]

For the lineWidth example I am noticing a difference on Linux where there isn't the 1px limit.

[IanLilleyT]

Ok, I added that to the checklist in #8113

[lilleyse]

Thanks @IanLilleyT , these fixes look good. Looking forward to the next batch in #8113 (after the release)