Drupal 10 compatibility fixes

Tested the patch. The patch applies cleanly and the functionality works as expected on Drupal 10 site.

..external_link_popup % git apply 8.x-1.12_external_link_popup_D10_Compatible.patch -v 
Checking patch external_link_popup.info.yml...
Checking patch external_link_popup.libraries.yml...
Checking patch js/dialog.js...
Applied patch external_link_popup.info.yml cleanly.
Applied patch external_link_popup.libraries.yml cleanly.
Applied patch js/dialog.js cleanly.

• Setup Drupal 10 site.
• Clone the module repository
• Applied the patch on 8.x-1.x branch.
• Enabled the module and verified the functionality

Thanks, I'll check Drupal versions where core/once and core/jquery.once available, and include the patch in a new release soon.

Automatically closed - issue fixed for 2 weeks with no activity.