[FR]: NSSecureCoding support

[Juan2662]

Description

Hi guys, I notice that some chunks in the code in iOS (like FirebaseMessaging) is using NSCoding protocol
I know you are working on that incrementally, but I would like to know when can we have full support for NSSecureCoding in all products?

API Proposal

No response

Firebase Product(s)

Messaging

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[paulb777]

A git grep shows the following NSCoding occurrences in Messaging and Database:

 $ git grep NSCoding
FirebaseDatabase/Sources/Persistence/FPendingPut.h:@interface FPendingPut : NSObject <NSCoding>
FirebaseDatabase/Sources/Persistence/FPendingPut.h:@interface FPendingPutPriority : NSObject <NSCoding>
FirebaseDatabase/Sources/Persistence/FPendingPut.h:@interface FPendingUpdate : NSObject <NSCoding>
FirebaseMessaging/Sources/Token/FIRMessagingAPNSInfo.h:@interface FIRMessagingAPNSInfo : NSObject <NSCoding, NSCopying>
FirebaseMessaging/Sources/Token/FIRMessagingAPNSInfo.m:#pragma mark - NSCoding
FirebaseMessaging/Sources/Token/FIRMessagingTokenInfo.h:@interface FIRMessagingTokenInfo : NSObject <NSCoding>
FirebaseMessaging/Sources/Token/FIRMessagingTokenInfo.m:#pragma mark - NSCoding

[paulb777]

Only updating Messaging for now. FPendingPut in RTDB does not have tests and may only be used in an outdated code path.