[ReactNative] Add RCTAssertThread and restrict -[UIManager addUIBlock:] to _shadowQueue

Summary:
@public

Add `RCTAssertThread` to `RCTAssert.h` for convenience when checking the current/queue,
it accepts either a `NSString *`, `NSThread *` or `dispatch_queue_t` as the object to be checked

Also add a check to `-[RCTUIManager addUIBlock:]` - There was a discussion on github (https://github.com/facebook/react-native/issues/1365)
due to the weird behavior caused by calling it from a different thread/queue (it might be added after `batchDidComplete` has been called
and will just be dispatched on the next call from JS to objc)

Test Plan:
Change `-[RCTAnimationExperimentalManager methodQueue]` to return `dispatch_get_main_queue()` and run the 2048 example,
it should dispatch with a helpful message (screenshot on the comments)

React/Base/RCTProfile.m

@@ -13,8 +13,8 @@
 
 #import <UIKit/UIKit.h>
 
+#import "RCTAssert.h"
 #import "RCTDefines.h"
-#import "RCTLog.h"
 #import "RCTUtils.h"
 
 #if RCT_DEV
@@ -43,7 +43,7 @@ NSLock *_RCTProfileLock;
 #define RCTProfileAddEvent(type, props...) \
 [RCTProfileInfo[type] addObject:@{ \
   @"pid": @([[NSProcessInfo processInfo] processIdentifier]), \
-  @"tid": RCTThreadName([NSThread currentThread]), \
+  @"tid": RCTCurrentThreadName(), \
   props \
 }];