NoReflowTabBar 1.2.0 - Minimum button length and Delphi compatibility

This release adds BarLayoutButtons.MinimumLength.

When BarLayoutButtons.ForcedLength is 0, button length is still computed from the item content as before, but it is raised to MinimumLength when the computed length is smaller.

When ForcedLength is greater than 0, the existing fixed-length behavior remains unchanged.

MinimumLength is a logical length constraint, not a physical X-axis width. It follows the component’s Length/Thickness model and remains compatible with horizontal and vertical bar orientations.

For vertically stacked content, where the glyph is logically above or below the text, the glyph/text block is centered in the remaining usable area when MinimumLength enlarges the button. Signals remain anchored at their normal positions.

This release also adds conditional compilation around newer VCL StyleServices(Control) calls, so older Delphi versions can fall back to global VCL style services.

Additional source comments were added around the canonical horizontal layout pipeline to avoid regressions where vertical orientations would accidentally be handled as a separate final-coordinate layout.