Extend and improve attachment browsing and usability in rich-text link pop-up

A customer has requested that the attachment tab in the link pop-up be improved in order to be able to navigate to other attachments other than those stored specifically on the individual page.

The customer expressed frustration in not being able to easily link to attachments stored on other pages, like child and parent pages, other attachments in the space, and other attachments in their Confluence instance.

At a mimimum they wanted the ability to be able to instantly see child and parent page attachments, and be able to easily navigate to attachments stored in the space or on other pages (all from within the link pop-up).

The customer also wanted the ability to search for attachments from within the link pop-up, either from the search tab, or from the attachment tab (currently searching from the link pop-up search tab, is restricted to pages only).