feat(admin-ui): DataTable + Skeleton components

[leopuleo]

Changes

This PR introduces two new components and improves many others.

Skeleton

The Skeleton component displays the loading state throughout the admin app. It follows the shadcn/ui specifications and may be updated as we await the final designs.

The previous Skeleton component used the react-loading-skeleton package, now removed.

Table + DataTable

These two components are used to display data across multiple admin app views. The Table component provides the backbone components and is used internally by DataTable, which handles data and column definitions.

The DataTable component will receive improvements in the future, migrating it to a first-test architecture approach.

Other improvements

Checkbox
Integrating the Checkbox component within the DataTable revealed several enhancements:

• The label prop is no longer required, enhancing component alignment when not supplied.
• We are forcing the check icon size and color: while using it inside a DropdownMenu component, its size and color were slightly odd.

How Has This Been Tested?

Jest + Manual