Reverted a change to the type for the serverId of a TSAttachment (change didn't match the protobuf)

SessionMessagingKit/Jobs/AttachmentUploadJob.swift

@@ -66,7 +66,7 @@ public final class AttachmentUploadJob : NSObject, Job, NSCoding { // NSObject/N
         guard let stream = TSAttachment.fetch(uniqueId: attachmentID) as? TSAttachmentStream else {
             return handleFailure(error: Error.noAttachment)
         }
-        guard !stream.isUploaded else { return handleSuccess(stream.serverId) } // Should never occur
+        guard !stream.isUploaded else { return handleSuccess("\(stream.serverId)") } // Should never occur
         
         let storage = SNMessagingKitConfiguration.shared.storage
         if let openGroup = storage.getOpenGroup(for: threadID) {
@@ -124,8 +124,13 @@ public final class AttachmentUploadJob : NSObject, Job, NSCoding { // NSObject/N
         stream.isUploaded = false
         stream.save()
         upload(data).done(on: DispatchQueue.global(qos: .userInitiated)) { fileId in
+            guard let intFileId: UInt64 = UInt64(fileId) else {
+                onFailure?(HTTP.Error.parsingFailed)
+                return
+            }
+            
             let downloadURL = "\(FileServerAPI.server)/files/\(fileId)"
-            stream.serverId = fileId
+            stream.serverId = intFileId
             stream.isUploaded = true
             stream.downloadURL = downloadURL
             stream.save()

SessionMessagingKit/Sending & Receiving/Attachments/TSAttachment.h

@@ -23,7 +23,7 @@ typedef NS_ENUM(NSUInteger, TSAttachmentType) {
 // The attachmentSchemaVersion and serverId properties only apply to
 // TSAttachmentPointer, which can be distinguished by the isDownloaded
 // property.
-@property (atomic, readwrite) NSString *serverId;
+@property (atomic, readwrite) UInt64 serverId;
 @property (atomic, readwrite, nullable) NSData *encryptionKey;
 @property (nonatomic, readonly) NSString *contentType;
 @property (atomic, readwrite) BOOL isDownloaded;

SessionMessagingKit/Sending & Receiving/Attachments/TSAttachment.m

@@ -27,7 +27,7 @@ NSUInteger const TSAttachmentSchemaVersion = 4;
 
 // This constructor is used for new instances of TSAttachmentPointer,
 // i.e. undownloaded incoming attachments.
-- (instancetype)initWithServerId:(NSString *)serverId
+- (instancetype)initWithServerId:(UInt64)serverId
                    encryptionKey:(nullable NSData *)encryptionKey
                        byteCount:(UInt32)byteCount
                      contentType:(NSString *)contentType

SessionMessagingKit/Sending & Receiving/Attachments/TSAttachmentPointer.m

@@ -170,7 +170,7 @@ NS_ASSUME_NONNULL_BEGIN
     // uniqueId.
     if (attachmentSchemaVersion < 2 && self.serverId == 0) {
         // For legacy instances, try to parse the serverId from the uniqueId.
-        self.serverId = self.uniqueId;
+        self.serverId = (UInt64)[self.uniqueId integerValue];
     }
 }