chore(elicitation): improve enum schema builder, small changes of elicitation builder

[pbezglasny]

Motivation and Context

Improve enum elicitation builder: switch to typesage implementation with better readability

Also:

• set legacy return type for required_enum/optional_enum to match previous version return type
• fix deprecation version to correct next version

How Has This Been Tested?

Unit/integration tests

Breaking Changes

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

[alexhancock]

Can you provide more context on the motivation behind the changes?