Apollo authorization directives

[eriksulymosi]

Resolves #

• Added or updated tests
• Documented user facing changes

Changes

This PR introduces support for Apollo-style declarative authorization directives within Lighthouse. This allows schemas to better align with Apollo Router / Federation standards for authorization handled at the gateway or subgraph level.

Key additions:

• Introduced Apollo Authorization Directives (e.g., @authenticated, @requiresScopes, @policy) to control field and type accessibility.
• Integrated the directive definitions into the schema generation and validation pipeline.
• Added corresponding tests to ensure schema syntax and directive handling work seamlessly with standard Apollo federation setups.

Breaking changes

None. This is a purely additive feature and does not affect existing @can, @auth or @guard directives implemented natively by Lighthouse.