2611 rename fetch data (#2689)

* Replace fetch data with preload terminology
- Deprecate `-fetchData` and `-clearFetchedData` in favor of `-preload` and `-clearPreloadedData`
- Move `-setNeedsPreload`, `-recursivelyPreload` and `-recursivelyClearPreloadedData` to ASDisplayNode+FrameworkPrivate.h
- Update internal implementation, comments and tests

* Folllow up on #2642:
- Remove -preload and -clearPreloadedData in favor of -didEnterPreloadState and -didExitPreloadState.
- -didEnterPreloadState and -didExitPreloadState call the deprecated -fetchData and -clearFetchedData methods if they are overriden.

* Missed one in a test

* Get rid of behavior change for now.

* Revert more behavior changes, fix tests.

* Don't need these anymore.

AsyncDisplayKit/ASVideoNode.mm

@@ -11,6 +11,7 @@
 #import <AVFoundation/AVFoundation.h>
 #import "ASDisplayNodeInternal.h"
 #import "ASDisplayNode+Subclasses.h"
+#import "ASDisplayNode+FrameworkPrivate.h"
 #import "ASVideoNode.h"
 #import "ASEqualityHelpers.h"
 #import "ASInternalHelpers.h"
@@ -365,9 +366,9 @@ static NSString * const kRate = @"rate";
   }
 }
 
-- (void)fetchData
+- (void)didEnterPreloadState
 {
-  [super fetchData];
+  [super didEnterPreloadState];
   
   ASDN::MutexLocker l(__instanceLock__);
   AVAsset *asset = self.asset;
@@ -405,9 +406,9 @@ static NSString * const kRate = @"rate";
   }
 }
 
-- (void)clearFetchedData
+- (void)didExitPreloadState
 {
-  [super clearFetchedData];
+  [super didExitPreloadState];
   
   {
     ASDN::MutexLocker l(__instanceLock__);
@@ -505,10 +506,10 @@ static NSString * const kRate = @"rate";
 
 - (void)_setAndFetchAsset:(AVAsset *)asset url:(NSURL *)assetURL
 {
-  [self clearFetchedData];
+  [self didExitPreloadState];
   _asset = asset;
   _assetURL = assetURL;
-  [self setNeedsDataFetch];
+  [self setNeedsPreload];
 }
 
 - (void)setVideoComposition:(AVVideoComposition *)videoComposition
@@ -617,7 +618,7 @@ static NSString * const kRate = @"rate";
   }
 
   if (_player == nil) {
-    [self setNeedsDataFetch];
+    [self setNeedsPreload];
   }
 
   if (_playerNode == nil) {