FB10198317 - Swift Charts: AxisValueLabel color does not change

content.txt

When setting `foregroundStyle` on a `AxisValueLabel`, the rendered text color does not change.

Example Code:

```
Chart([(0,0), (1,1), (2, 2), (3, 3), (4, 4)], id: \.0) { point in
                LineMark(x: .value("X", point.0), y: .value("Y", point.1))
            }
            .chartYAxis {
                AxisMarks { _ in
                    AxisTick()
                        .foregroundStyle(.red)
                    AxisGridLine()
                        .foregroundStyle(.red)
                    AxisValueLabel()
                        .foregroundStyle(.red)
                }
            }
```

Expected result: The AxisValueLabel is colored red.
Actual result: The AxisValueLabel is colored either light gray (dark mode), or dark gray (light mode), but never red.

This is a problem because we are often rendering charts in front of a fixed (dark) background. So we need the axis labels to have a certain, colorscheme-independent, color.

screenshot.png

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