Update RFC 0016 to reflect delivered work and TP plans

[maksymvavilov]

Update RFC 0016 to reflect delivered work and TP plans

Description

RFC 0016 (Egress Gateway Support for Kuadrant) still has status "Draft" but the initial goals have been fully delivered in RHCL 1.4. The RFC should be updated to reflect the current state and point to the TP work as the next phase.

Acceptance Criteria

• Update RFC status from "Draft" to an appropriate status reflecting completed initial delivery
• Add a "Delivered" or "Status" section summarizing what was completed in 1.4 (AuthPolicy, RLP, DNS routing, credential injection, MCP Gateway, docs, dev env)
• Update the Future Work section to reflect what is now in progress for TP (observability, TRLP, TelemetryPolicy) vs what remains future (AuthTokenManagementPolicy, DNSPolicy egress mode, etc.)
• Remove or update any language that reads as speculative for things that are now confirmed (e.g., "hypothesis" about policies working on egress)