fix: DH-21616: Databar overrides text color when using format prop

[gzh2003]

For DH-21616. Databar cells were using the databar bar color for both the bar and the text, ignoring any explicit text color set via formatting.

Companion PR: deephaven/deephaven-plugins#1323

[codecov]

Codecov Report

❌ Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.55%. Comparing base (0cab21d) to head (e039cef).
⚠️ Report is 32 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/grid/src/DataBarCellRenderer.ts	0.00%	5 Missing ⚠️
packages/grid/src/MockDataBarGridModel.ts	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2640      +/-   ##
==========================================
+ Coverage   49.48%   49.55%   +0.07%     
==========================================
  Files         772      774       +2     
  Lines       43738    43871     +133     
  Branches    11066    11295     +229     
==========================================
+ Hits        21643    21740      +97     
- Misses      22077    22085       +8     
- Partials       18       46      +28     

Flag	Coverage Δ
unit	49.55% <0.00%> (+0.07%)	⬆️

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[mofojed]

The Grid component by design is generally dumb/explicit about what it's rendering; the GridModel is basically explicitly what it's going to render (colorForCell, textForCell, etc). The brains/logic are designed to be in the specific implementations of the GridModel (e.g. IrisGridModel, or UITableModel).
By putting the textColor explicitly in the DataBarOptions, we're keeping that logic of "user explicitly set a format value" in the UITableModel.

[mofojed]

Should just be "the text color for the cell". How it is derived is not determined from within this context.
If we took an optional textColor here and fell back to the color, we could say that. But this behaviour documented here is not accurate from this context.
And then the color attribute should have a doc string for "Color of the databar", maybe explain how you can pass a gradient.