feat: add support for disabling output validation for tools

[antoniomdk]

Motivation and Context

• When using MCP as a OpenAPI proxy, sometimes the downstream server doesn't respect 100% the json schema.
• If the downstream server has output validation, then validating the output again is redundant.

How Has This Been Tested?

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