chore - improve error message when using access token to authenticate

[publi0]

What does this PR do?

todo

Improvements to error handling and logging:

• mgc/core/auth/auth.go: Added import for the errors package to handle error creation.
• mgc/core/auth/auth.go: Enhanced the AccessToken method to log errors using logger().Errorw and return more descriptive error messages when failing to refresh the access token.

How Has This Been Tested?

• Unit Tests: Describe the unit tests you have written and their outcomes.
  Unit tests ok

• Manual Testing: Explain the manual testing process, including steps taken and evidence such as screenshots or logs.
  Manual testing ok

Checklist

• I have run Pre commit pre-commit run --all-files
• My code follows the style guidelines of this project
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

Screenshots/Videos

Copilot reviewed 1 out of 1 changed files in this pull request and generated no suggestions.