Add delegation and request lifecycle APIs

[humandebri]

Summary

• Add constrained child delegation issuance without exposing session private keys.
• Add split update submission/completion APIs that return the 32-byte IC ingress request ID before polling.
• Add certified single-shot request status, per-request expiry and nonce options, and persistable signed query/update envelopes.
• Preserve existing Raw, Candid, and typed query/call signatures, including method references.

Validation

• qrun -- swift test
• Swift 6 strict concurrency CI
• iOS Simulator CI
• git diff --check

Release

• Prepare ICNativeClient 0.8.0 release notes.
• Keep stored sessions, generated bindings, and default wire formats compatible.