[6.x] Fix Bard Link Toolbar

[duncanmcclean]

This pull request fixes various with the Bard Link Toolbar:

• Corrects icon names
• Fixes an issue where selecting a link type would close the popover.
  • This was happening due to the click event originating in the Combobox's portal, which is considered "outside" of the Popover.
• Fixes an error when opening the entry selector
  • This was due to an added conditional around the existing button, meaning it wouldn't be rendered in some conditions.
  • This PR fixes it by adding a new openSelector method instead.

Fixes #13195

[jackmcdade]

https://github.com/user-attachments/assets/941ca771-029d-4529-bc4d-68ad0aaed426

Seems to still need a bit 'o love 🤔

[duncanmcclean]

@jackmcdade Better now?