Added functions read_resource and resource_templates from client/session.py to client/session_group.py

[AishwaryaKalloli]

Adding functionalities to client/session_group.py that are present in client/session.py.

Motivation and Context

Saw this issue where the user wants capabilities to broadcast notification to all the connected clients from a server.
Saw a similar implementation on client side at client/session_group.py. Wanted to make all the functions available here first, also helps me understand the how to implement server/session_group.py better.

If this looks good I can add the remaining functions to client session group first then create server session group.

How Has This Been Tested?

Tested through unit tests.

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