Enable nested act/sub claims for delegation chains

[Bin4yi]

Problem

Current implementation does not handle logging act sub claims in multi-level delegation scenarios where tokens are exchanged through multiple actors in a chain. This limitation prevents:

• Tracking the complete delegation chain in enterprise workflows
• Auditing and compliance requirements in complex delegation scenarios
• Proper authorization decisions based on the full actor chain

Proposed Solution

Implement support for nested act/sub claim structures:

• Create recursive claim parser to handle deeply nested act/sub structures

• Preserve existing act chains when adding new delegation layers

• Add extractActorChain() utility with comprehensive logging for debugging

• PRRA: Add Support nested act claim with azp and multi-audience in token request wso2-extensions/identity-inbound-auth-oauth#3028

Alternatives

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Version

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Developer Checklist

• [Behavioural Change] Does this change introduce a behavioral change to the product?
•  ↳ Approved by team lead
•  ↳ Label impact/behavioral-change added
• [Migration Impact] Does this change have a migration impact?
•  ↳ Migration label added (e.g., 7.2.0-migration)
•  ↳ Migration issues created and linked
• [New Configuration] Does this change introduce a new configuration?
•  ↳ Label config added
•  ↳ Configuration is properly documented