Add support for numbered pages and sections

Antora does not offer a feature built-in for adding automatic numbering to all pages in a component.

It is possible to add :sectnums: so that sections within a page get numbered automatically (and it is also possible to exclude sections this way), but neither does this include a number for the page title (i.e. the chapter) nor add that number in front of the section.

The idea now would be to add numbers automatically based on the navigation structure.

• Numbers must be sequential within each component-version combination and start from one.
• It shall be possible to exclude certain pages
• It may be possible to exclude certain sections (tbd)
• TBD: Consider the level within the navigation structure for the number to be used to increase (i.e. "*" = first level, "**" = second level etc.).