rename sessionCipher to sessionStoreQueue

// FREEBIE

src/Messages/OWSMessageSender.m

@@ -993,7 +993,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
             __block NSException *encryptionException;
             // Mutating session state is not thread safe, so we operate on a serial queue, shared with decryption
             // operations.
-            dispatch_sync([OWSDispatch sessionCipher], ^{
+            dispatch_sync([OWSDispatch sessionStoreQueue], ^{
                 @try {
                     messageDict = [self encryptedMessageWithPlaintext:plainText
                                                           toRecipient:recipient.uniqueId

src/Messages/TSMessagesManager.m

@@ -251,7 +251,7 @@ NS_ASSUME_NONNULL_BEGIN
             return;
         }
 
-        dispatch_async([OWSDispatch sessionCipher], ^{
+        dispatch_async([OWSDispatch sessionStoreQueue], ^{
             NSData *plaintextData;
 
             @try {
@@ -300,7 +300,7 @@ NS_ASSUME_NONNULL_BEGIN
             return;
         }
 
-        dispatch_async([OWSDispatch sessionCipher], ^{
+        dispatch_async([OWSDispatch sessionStoreQueue], ^{
             NSData *plaintextData;
             @try {
                 // Check whether we need to refresh our PreKeys every time we receive a PreKeyWhisperMessage.

src/Util/OWSDispatch.h

@@ -15,7 +15,7 @@ NS_ASSUME_NONNULL_BEGIN
  * Signal protocol session state must be coordinated on a serial queue. This is sometimes used synchronously,
  * so never dispatching sync *from* this queue to avoid deadlock.
  */
-+ (dispatch_queue_t)sessionCipher;
++ (dispatch_queue_t)sessionStoreQueue;
 
 /**
  * Serial message sending queue

src/Util/OWSDispatch.m

@@ -18,12 +18,12 @@ NS_ASSUME_NONNULL_BEGIN
     return queue;
 }
 
-+ (dispatch_queue_t)sessionCipher
++ (dispatch_queue_t)sessionStoreQueue
 {
     static dispatch_once_t onceToken;
     static dispatch_queue_t queue;
     dispatch_once(&onceToken, ^{
-        queue = dispatch_queue_create("org.whispersystems.signal.sessionCipher", NULL);
+        queue = dispatch_queue_create("org.whispersystems.signal.sessionStoreQueue", NULL);
     });
     return queue;
 }