Manual Sync: Add Alert Notifications

What does this MR do?

This is a 4 steps MR, tackling gitlab-org/gitlab#325156. The backend implementation was already done but given the frontend requirements have changed, there's gonna be some updates from the backend as well.

In this MR we introduce a component responsible to handle the user notifications for successful or failing (manual) sync. The component will be plugged into the main app in the scope of the second step.

The feature is behind an Application setting. Steps to test locally are provided below.

1	frontend to add the alerts and display logic	👈 you are here
2	frontend to show the sync button and connect with backend	tbd
3	frontend write specs	tbd
4	backend to modify the response from the sync endpoint	tbd

To test the changes locally

1. Use Rails console to run:

ApplicationSetting.current.update(cloud_license_enabled: true)

2. Use the following patch:

• Idle: idle.patch
• Success: success.patch
• Failure: failure.patch

3. Navigate to admin/cloud_license

Screenshots (strongly suggested)

Idle	Sync success	Sync failure

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because no UI changes.
• [-] 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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team