XD-1807 Paging support for repositories

- Add utility class `PagingUtility` that returns the page implementation of
the given `Comparable` list
  - Make `ModuleMetadata`, `ContainerAttributes` and `ModuleDefinition` of type
`Comparable`
  - Update all the repositories `findAll(Pageable)` to use type specific
PageUtility's paged data
- Fix tests
I think PagingUtility deserves its own unit test, covering the corner cases of 0-sized list, page==fullSize, page<fullSize, page>fullSize, etc.