Improve loading UX in the License Management list

• Related issue: #9107 (closed)

What does this MR do?

This MR improves the UX in the license management admin area by tweaking a few UI elements and behaviors:

• The Submit button to add a new managed license now uses the success (green) variant.
• When adding a new managed license, we now show a loading indicator in the submit button while the license is being added (request #1) and the list is being refreshed (request #2). Once both requests have completed, we close the form and re-render the list at the same time.
• When updating or removing a managed license, we now show a loading spinner on that license's row instead of replacing the whole list with a loading spinner.

Screenshots

	Before	After
Adding licenses	before_adding_licenses	after_adding_licenses
Updating licenses	before_updating_licenses	after_updating_licenses
Removing licenses	before_removing_licenses	after_removing_licenses

How to test this?

1. In any project, go to Settings > CI/CD > License Compliance.
2. Add, update and remove licenses at will!

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done