Implemented basic Pager component & OffsetPager<T>

[DarthPedro]

• Added the D20Tek.BlazorComponents.Pager package with the theme-agnostic Pager component:
  • Fully controlled pagination via CurrentPage/CurrentPageChanged, PageSize/PageSizeChanged, and TotalItems.
  • Opt-in previous/next, numbered pages, first/last buttons, a "Page X of Y" description, and a page-size selector.
  • MudBlazor-style anchored page windowing driven by two knobs, BoundaryCount (default 1) and MiddleCount (default 5, centered on the current page), with leading/trailing ellipsis.
  • Scoped CSS styled from currentColor (no static stylesheet to link) that adapts to any light, dark, or custom theme.
  • Responsive collapse of subcomponents via CSS container queries as the container narrows; opt out with DisableResponsive="true".
  • Configurable control labels and Size support.
• Added the D20Tek.BlazorComponents.Vertically package with the OffsetPager<T> component:
  • Wraps Pager for the D20Tek.Vertically paging types, binding a PageOf<T> result to the pager controls.
  • Raises OnPageQuery with a new one-based PagedRequest (PageNumber plus PageSize) on navigation or page-size changes, resetting to page 1 when the page size changes.
• Added both new packages to the D20Tek.BlazorComponents.All meta-package.
• Added a Pager sample page to the D20Tek.FullSample.Wasm sample app.