Tracking issue for settings

[ok-nick]

This is a tracking issue for settings work.

Major implementation steps:

• Plumb settings by-value down the SDK feat: Make settings not thread-local #1444
• Document and publicize settings structs feat: add settings structs to the public API #1447
• Pass settings (and resolvers) into Reader feat: impl ReaderBuilder #1465
• Pass settings (and resolvers) into Builder
• Generate cross-language documentation for settings Generate cross-language documentation for settings #1473
• Clean up settings plumbing down the SDK

Related issues:

• Configure remote manifests with settings instead of features Configure fetching remote manifests with a setting versus feature flag #1434
• Rename trust to c2pa_trust Rename Settings trust entry to c2pa_trust to distinguish from cawg_trust? #1314
• Configure CAWG with settings CAWG signing integration for c2patool #748
• Configure CAWG via CLI in addition to settings Configure CAWG trust via CLI? #1467
• Revising public API to take settings structs Consider revising public APIs to take Settings struct #1454
• Move to settings-based configuration Move to Settings based configuration and Manifest Definition #1381
• Expose API for passing in HTTP resolvers Expose API for passing in sync/async HTTP resolvers #1366

Other unresolved questions:

• Should we introduce a builder for the Builder?
• How should we add settings to Ingredients?
• How should we add settings to IdentityAssertion::validate_partial_claim?
• What should we do with our current thread-local settings?