Check all methods & capabilities

[kfischer-okarin]

I added all missing methods & capability checks (and refactored both tests & implementation to be more declarative)

Motivation and Context

Not all capabilities and methods were checked.

How Has This Been Tested?

Not really - but the existing server 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

This is not yet adding the actual capability checks to the notification methods - that I'd add in another short PR