Polish blocked repositories page layout

[gtsiolis]

Problem to solve

Follow-up UX from #11446.

• 1. Use red text color for the delete option in the more actions dropdown, see [dashboard] BlockedRepo UI #11446 (comment).
• 2. Improve empty input validation error. Replace Empty RegEx! with Repository URL can not be empty.
• 3. Improve table design (thinner rows in height)
• 4. Improve table header (borderless design)
• 5. Improve table binary option for indicating blocking users toggle with text or an icon, see [dashboard] BlockedRepo UI #11446 (comment).
• 6. Improve input placeholder, see [dashboard] BlockedRepo UI #11446 (comment).
• 7. Use an alert component to inform user about search input flexibity or limitations, see [dashboard] BlockedRepo UI #11446 (comment).
• 8. Use an alert component to inform the user that RegEx is supported while adding a new blocked repository.
• 9. Remove the Delete table header, the more actions column does not need a table header.
• 10. Move the Block User slightly more to the left for better white space usage and visual balance.
• 11. Improve table typography, see colors, font size and font weight in the linked design specs below.
• 12. Rename Block User to Block Users in the new blocked repository modal.

Additional things to consider:

• 13. Adding the EDIT functionality using the same modal.
• 14. Use an alert component (warning variant) to warn users, this can affect all instance users.
• 15. Surface the admin user who added each blocked repository, for system visibility.
• 16. Improve dark theme colors. 🌔
• 17. Introduce Updated date column and indicate sorting order.
• 18. Remove the Blocked Users section within the modal when deleting a blocked repository. ❗

See design specs.

Block Users (Text)	Block Users (Icon)	New Blocked Repository (Modal)

[gtsiolis]

@geropl I was planning to mark these as a ~good-first-issue but saw that you already opened #11462 to address most of these issues. Feel free to leave out of #11462 anything that increases the scope of the PR as a new follow-up issue.

[geropl]

15. Surface the admin user who added each blocked repository, for system visibility.

Excellent idea! 💡 I long planned to add an epic for this, now there is one.

[gtsiolis]

@geropl I've silently added in the issue description 4-5 more tasks to keep track of these but should be fine to also break these into a separate issue if we'd like to unblock merging #11462.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.