Add Sendable annotations to Crypto Extras to reflect current sandability so that downstream packages can implement sendable conformance.
Modifications
Add Sendable conformance to some missed public symbols.
RSA public and private keys are now marked sendable with their backing storage on darwin OS marked unchecked sendable until SecKey from security framework has sendability annotations
Motivation
Add Sendable annotations to Crypto Extras to reflect current sandability so that downstream packages can implement sendable conformance.
Modifications
Result