[RAT-2480] Removing unnecessary dictionary allocation

[lopezt-unity]

Purpose of this PR

The ColorUtility.ColorNameLookup dictionary was taking too much space in builds, as reported by some users and does not have any other use than displaying a nice name in an optional notification in the SceneView when applying colors to a face, vertex or edge.

This PR remove that dictionary as the cost here seems unrelevant.

Links

Jira: https://jira.unity3d.com/browse/RAT-2480

Comments to Reviewers

[List known issues, planned work, provide any extra context for your code.]

[u-pr]

The PR looks good overall. The changes significantly reduce binary size and memory overhead by removing large utility dictionaries. Two minor observations regarding public API breaking changes and documentation clarity were noted.

_{🤖 Helpful? 👍/👎}

[u-pr]

While removing the ColorNameLookup dictionary is a significant performance win for binary size and runtime memory, note that removing the public static string GetColorName method is a breaking change for the public API. If this color-naming functionality remains useful for Editor-side tooling, have you considered moving the logic and dictionary to an Editor assembly instead of deleting it? This would preserve the feature for developers while keeping the Runtime build lean. Additionally, it may be worth verifying if supporting types like CIELabColor or XYZColor are now orphaned and should also be moved or removed.

_{🤖 Helpful? 👍/👎}

[u-pr]

Minor nit: The phrase 'allocate unnecessary large space' is slightly unclear. Have you considered rephrasing to 'Removed a large utility dictionary to reduce binary size and runtime memory overhead' or similar?

_{🤖 Helpful? 👍/👎}

[codecov-github-com]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
Editor/EditorCore/VertexColorPalette.cs	0.00%	1 Missing ⚠️

@@           Coverage Diff           @@
##           master     #662   +/-   ##
=======================================
  Coverage   36.05%   36.06%           
=======================================
  Files         277      277           
  Lines       34909    34911    +2     
=======================================
+ Hits        12588    12589    +1     
- Misses      22321    22322    +1     

Flag	Coverage Δ
probuilder_MacOS_6000.0	34.60% <0.00%> (+0.01%)	⬆️
probuilder_MacOS_6000.3	34.60% <0.00%> (+0.01%)	⬆️
probuilder_MacOS_6000.4	34.59% <0.00%> (+0.01%)	⬆️
probuilder_MacOS_6000.6	34.59% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
Runtime/Core/ColorUtility.cs	0.00% <ø> (ø)
Editor/EditorCore/VertexColorPalette.cs	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes