fix: RN Intercom on iOS run not on main thread

When running Intercom I noticed that the app is lagging on the first usage of any Intercom method (subsequent
usages seems to be OK). When checking logs in XCode, I noticed that there's warning "- [UIApplication
supportsMultipleScenes] must be used from main thread only" for any method that is run as a first one in the app.

To handle all possible cases, I made a patch where I declare the main queue as a `- methodQueue`
(https://reactnative.dev/docs/native-modules-ios#threading)

Author: mateusz1913

ios/IntercomModule.m

@@ -21,6 +21,10 @@ @implementation IntercomModule
 
 RCT_EXPORT_MODULE()
 
+- (dispatch_queue_t)methodQueue {
+    return dispatch_get_main_queue();
+}
+
 + (void)initialize:(nonnull NSString *)apiKey withAppId:(nonnull NSString *)appId {
     NSString *version = @"0";
 
@@ -81,7 +85,7 @@ - (NSData *)dataFromHexString:(NSString *)string {
         [Intercom setDeviceToken:data failure:^(NSError * _Nullable error) {
             reject(SEND_TOKEN_TO_INTERCOM, @"Error in sendTokenToIntercom", error);
         }];
-        
+
         resolve(@(YES));
     } @catch (NSException *exception) {
         reject(SEND_TOKEN_TO_INTERCOM, @"Error in sendTokenToIntercom", [self exceptionToError:exception :SEND_TOKEN_TO_INTERCOM :@"sendTokenToIntercom"]);
@@ -229,7 +233,7 @@ - (NSData *)dataFromHexString:(NSString *)string {
 
 RCT_EXPORT_METHOD(fetchHelpCenterCollections:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject) {
     [Intercom fetchHelpCenterCollectionsWithCompletion:^(NSArray<ICMHelpCenterCollection *> *_Nullable collections, NSError *_Nullable error) {
-        
+
         if (collections != nil) {
             NSArray *parsedCollections = [IntercomHelpCenterHelpers parseCollectionsToArray:collections];
             resolve(parsedCollections);