Improve the link insertion dialog

References:

• https://design.xwiki.org/xwiki/bin/view/Proposal/ProposalforUXimprovementstothelinkdialog
• https://forum.xwiki.org/t/proposal-for-ux-improvements-to-the-link-dialog/14838/

The goal of this task is to improve the link insertion dialog of Blocknote, with more advanced concepts than what is currently proposed.
See the reference design linked above.

Important point to consider:

• An important initial step is to check if there are technical constraints limiting our ability to implement the proposed design.
• Blocknote is published as a reusable component, so it must be possible to contribute new kinds of links by extension (or to remove existing ones).
• Default link extensions must be published as individual packages to be reusable.