[Server] Add autoload check for enum types in ReferenceHandler

[joshuatam]

Motivation and Context

Some old framework is using autoload to include with the typeName directly, e.g. include(ini.php) when the typeName is ini.

If the typeName is the arbitrary type, set autoload in enum_exists to false

How Has This Been Tested?

Yes

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

None

[chr-hertel]

Hey @joshuatam, thanks for reaching out and bringing the patch. Can you help me understand the issue here? What's happening without this patch?
E.g. what's the error you're running into - is there a way to reproduce that?