Fix globe baselayer error

[Masty88]

Description

This PR adds a check to prevent using baseLayer when globe is disabled, which would cause render errors.
The check throws a DeveloperError with a clear message to help developers understand and fix the issue.

The fix:

• Adds validation in the Viewer constructor to check for invalid baseLayer usage
• Throws DeveloperError with clear message when attempting to use baseLayer with globe: false
• Allows valid cases like baseLayer: false or when globe is not explicitly disabled

Issue number and link

Fixes #12244

Testing plan

Added two new test cases in ViewerSpec.js:

1. Verifies error is thrown when baseLayer is provided with globe: false
2. Verifies no error when globe is false but baseLayer is not provided

Additional testing:

• Verified existing tests continue to pass
• Manually tested in Sandcastle to ensure valid configurations still work
• Verified error message is clear and helpful

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with "Fixed error when using baseLayer with globe disabled"
• I have added unit tests to ensure consistent code coverage
• I have updated the inline documentation
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @Masty88!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks for the PR @Masty88!