Only run "enable video calling" migration if user is registered.

// FREEBIE

Signal/src/environment/Migrations/OWS103EnableVideoCalling.m

@@ -3,8 +3,9 @@
 //
 
 #import "OWS103EnableVideoCalling.h"
-#import <SignalServiceKit/TSUpdateAttributesRequest.h>
+#import <SignalServiceKit/TSAccountManager.h>
 #import <SignalServiceKit/TSNetworkManager.h>
+#import <SignalServiceKit/TSUpdateAttributesRequest.h>
 
 // Increment a similar constant for every future DBMigration
 static NSString *const OWS103EnableVideoCallingMigrationId = @"103";
@@ -21,15 +22,26 @@ static NSString *const OWS103EnableVideoCallingMigrationId = @"103";
 {
     DDLogWarn(@"%@ running migration...", self.tag);
 
-    TSUpdateAttributesRequest *request = [[TSUpdateAttributesRequest alloc] initWithUpdatedAttributesWithVoice];
-    [[TSNetworkManager sharedManager] makeRequest:request
-                                          success:^(NSURLSessionDataTask *task, id responseObject) {
-                                              DDLogInfo(@"%@ successfully ran", self.tag);
-                                              [self save];
-                                          }
-                                          failure:^(NSURLSessionDataTask *task, NSError *error) {
-                                              DDLogError(@"%@ failed with error: %@", self.tag, error);
-                                          }];
+    // TODO: It'd be nice if TSAccountManager had a
+    //       [ifRegisteredRunAsync: ifNoRegisteredRunAsync:] method.
+    [[TSAccountManager sharedInstance] ifRegistered:YES
+                                           runAsync:^{
+                                               TSUpdateAttributesRequest *request = [[TSUpdateAttributesRequest alloc]
+                                                   initWithUpdatedAttributesWithVoice];
+                                               [[TSNetworkManager sharedManager] makeRequest:request
+                                                   success:^(NSURLSessionDataTask *task, id responseObject) {
+                                                       DDLogInfo(@"%@ successfully ran", self.tag);
+                                                       [self save];
+                                                   }
+                                                   failure:^(NSURLSessionDataTask *task, NSError *error) {
+                                                       DDLogError(@"%@ failed with error: %@", self.tag, error);
+                                                   }];
+                                           }];
+    [[TSAccountManager sharedInstance] ifRegistered:NO
+                                           runAsync:^{
+                                               DDLogInfo(@"%@ skipping; not registered", self.tag);
+                                               [self save];
+                                           }];
 }
 
 #pragma mark - Logging