SEP: Allow non-file URI schemes for Roots

[chughtapan]

Motivation and Context

This showcases the sdk changes for SEP-1573

How Has This Been Tested?

all new and existing tests pass

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

[maxisbey]

Closing this stale draft - feel free to reopen if SEP-1573 has movement.

_{AI Disclaimer}