fix: external link url disappears before the closing transition ends

[crnkovic]

Summary

https://app.clickup.com/t/862kj4b5v

Previously, the shown/hidden state depended on the URL being set or not, so we first had to clear the URL to get the modal to close, but since the modal has a transition, this created this visual bug. Now, the modal is managed by its own open state, so we can leave the URL in the state until the next external link modal is opened, at which point the URL is just replaced with the new one. This way, the URL will be visible even during the modal closing transition.

Screen.Recording.2023-11-06.at.10.43.27.mov

Checklist

• I checked my UI changes against the design and there are no notable differences
• I checked my UI changes for any responsiveness issues
• I checked my (code) changes for obvious issues, debug statements and commented code
• I opened a corresponding card on Clickup for any remaining TODOs in my code
• I added a short description on how to test this PR (if necessary)
• I added a storybook entry for the component that was added (if necessary)
• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged