Handle GlobalIDs with invalid resource names

What does this MR do?

A GID with an invalid model_name portion previously threw an unhandled NameError when parsed by Types::GlobalIDType due to #model_class calling constantize on the String:

GlobalID.new("gid://gitlab/invalid_name/7").model_class
# => NameError: wrong constant name invalid_name

The API client would receive our generic unhandled error response:

{
  "errors": [
    {
      "message": "Internal server error: wrong constant name <resource name>"
    }
  ]
}

This change handles this situation as a GraphQL::CoercionError and the error response for the client is:

{
  "errors": [
    {
      "message": "\"gid://gitlab/<resource name>/1\" does not represent an instance of <expected resource>"
    }
  ]
}

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• • ] 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