Run CLANGFORMAT on plugins

Summary:
This diff runs CLANGFORMAT lint on plugins. I have added CLANGFORMAT as the lint engined for objc files in xplat/sonar. Right now the iOS folder is not formatted according to CLANGFORMAT.

Ran `arc lint -a --paths-cmd "find ./iOS/Plugins -type f" --verbose`

Reviewed By: passy

Differential Revision: D19942173

fbshipit-source-id: 8b975b0a344df073b02d69cd1f9ee5629af2799d

iOS/Plugins/FlipperKitNetworkPlugin/SKIOSNetworkPlugin/SKIOSNetworkAdapter.mm

@@ -13,8 +13,8 @@
 
 @implementation SKIOSNetworkAdapter
 @synthesize delegate = _delegate;
-- (instancetype)init{
-  if (self=[super init]){
+- (instancetype)init {
+  if (self = [super init]) {
     _delegate = nil;
   }
   return self;