Surface import failure error when importing via url

What does this MR do and why?

Current state

Scenario: User starts a URL import and while the repo is being imported (and the project is being created) the user navigated away.

If a project import has just failed but the user navigated away from the import in progress page, yet stays within the created project, they don't see a failure error.

Note: currently when a URL import is in progress, the project is still created whether the import of the Repository failed or not. So the user can still go to the /<just-created-project> page and settings. This is why we're making it more clear to the user that the repo import has failed.

The fix

Modifies the _importing_alert.haml to alert the user that an import has failed as long as they are within the <group>/<just-created-project> page

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Navigate to one of your top level groups
2. Click create project => Import project => Repository by URL
3. You need a valid git repo url. Paste the https .git link as the url, enter the correct user name but the wrong password
4. Type in a name for the project. Pick your group under "Choose a group or namespace" and click Create project
5. You should see the Import in progress page for a time, then you are redirected as the import has failed.
6. You should see a dismissible banner when the import failed notifying that the import failed.
7. Navigate to the settings page for that project and the dismissable alert should be there as well

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Related to #195997