DynamicAssertion breaks Builder::sign_async on tokio

[duggaraju]

Since DynamicAssertion doesn't implement Send, ManifestDefintion and hence Builder are no longer Send. That means calling Builder::sign_async from an async runtime that requires send (e.g: tokio) would fail.

[github-jira-sync-bot]

✅ Jira issue https://jira.corp.adobe.com/browse/CAI-7678 is successfully created for this GitHub issue.

[gpeacock]

We have added an AsyncDynamicAssertion with Send support now.

[duggaraju]

@gpeacock looking at the latest code in the master branch I still see the AsyncDynamicAssertion only implements Sync and not Send

c2pa-rs/sdk/src/dynamic_assertion.rs

Line 88 in da13c79

pub trait AsyncDynamicAssertion: Sync {