Allow space pages export using a filter

The current way to export an entire space or some of its pages to PDF is to tick/untick all wanted pages in the "space operations => export pdf" page.
When we want to export many specific pages across a space, it becomes frequent to miss a page, and it takes time to select.

A nice feature would be to be able to select/restrict pages using a filter based on content and/or tags.

That way, we could easily generate an export of wanted pages without the hassle of checking/unchecking needed pages.