Built Controls For Color By Value

[lhawkman27]

Summary/Description

We need to build out controls for the ColorByValue functionality.
This will replace the colorByValue styling block in our current JSON Blob control.

• Metric/value column selector.
• Start/end colors.
• lower/upper bounds.
• breakpoint controls if still needed.

"colorByValue": {
    "breakpoints": [],
    "endColor": [207, 30, 14, 255],
    "lowerBound": 40,
    "startColor": [222, 214, 67, 255],
    "upperBound": 157,
    "valueColumn": "max_gust_mph"
  },

valueColumn: column dropdown selection
breakpoints control: text (number) entry fields(4)
endColor control: RGBA Selector or field entries (for R,G,B,A)
startColor control: RGBA Selector or field entries (for R,G,B,A)
lowerbound control: text (number) entry
upperbound control: text (number) entry

Motivation/Context

The JSON blob has been useful as a fast prototyping surface, but it is now carrying too much product behavior: category coloring, metric coloring, point sizing, legends, text overlay, styling, defaults, maybe more. That makes it hard for users, hard to validate, and easy for MVT/non-MVT behavior to drift.

Acceptance

• ColorByValue functionality works as expected
• non-MVT keeps current behavior; MVT has a clear follow-up path for stable domain calculation.
• Update documentation properly (Wiki, etc...)

Wiki Page:
https://github.com/raft-tech/GeoSet/wiki/GeoSet-Map-Layer#geojson-config