feat: add _meta to more objects

[felixweinberger]

Motivation and Context

Add _meta fields to additional MCP types. This PR updates the Python SDK to align with the protocol changes from modelcontextprotocol/modelcontextprotocol#710, which added _meta fields to several additional types in the MCP specification.

• Resource
• ResourceTemplate
• Tool
• TextContent
• ImageContent
• AudioContent
• Root

How Has This Been Tested?

uv run ruff check
uv run pytest

Breaking Changes

N/A

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

TypeScript equivalent modelcontextprotocol/typescript-sdk#630

[ihrpr]

Please can we make sure that model_config is in the end?

[felixweinberger]

Added

ResourceContentsSchema
PromptSchema
EmbeddedResourceSchema

As well to match modelcontextprotocol/modelcontextprotocol#710

[ihrpr]

Thank you!