Add error handling to code analytics

What does this MR do?

❗ Rebase and target master when !18395 (closed) is merged

This MR adds the error handling required for code analytics, i.e. when a 403 is returned from the API, the appropriate access denied error message is displayed.

This is behind the code_analytics feature flag introduced in !17618 (merged)

Code Analytics plan

The MR adds the chart for the following plan

Screenshots

Access denied error	General error i.e. 500

Does this MR meet the acceptance criteria?

Conformity

• [n/a] Changelog entry (This is behind a feature flag)
• [n/a] Documentation created/updated or follow-up review issue created
• 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

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:

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