Add comprehensive Range Bar Series documentation under Data Chart Range Series

[Copilot]

This PR adds the missing Range Bar Series documentation content under Data Chart range series and aligns it with existing range-series coverage expectations (Range Area / Range Column level of detail).

• Scope

  • Expanded topics/en/datachart-series-range-bar.adoc into a complete topic rather than a minimal stub.

• Topic content added

  • Added Overview clarifying orientation and axis usage (CategoryYAxis + NumericXAxis).
  • Added Class Hierarchy section showing RangeBarSeries inheritance in relation to RangeColumnSeries / RangeAreaSeries.
  • Added Comparison with Range Column Series table (orientation, axes, base class, vertical/bar flags).
  • Added Data Format section with concrete sample payload.
  • Added Related Series links (RangeColumnSeries, RangeAreaSeries, BarSeries).

• What remained intact

  • Preserved existing Requirements, XAML example, Key Properties, and Related Topics structure, extending only where needed.

== Comparison with Range Column Series

[options="header", cols="a,a,a"]
|===
| Feature | Range Column Series | Range Bar Series
| Orientation | Vertical columns | Horizontal bars
| Category Axis | CategoryXAxis (horizontal) | CategoryYAxis (vertical)
| Value Axis | NumericYAxis (vertical) | NumericXAxis (horizontal)
|===