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/ASDisplayNode.h

@@ -478,31 +478,6 @@ extern NSInteger const ASDefaultDrawingPriority;
  */
 - (void)recursivelyClearContents;
 
-/**
- * @abstract Calls -clearFetchedData on the receiver and its subnode hierarchy.
- *
- * @discussion Clears any memory-intensive fetched content.
- * This method is used to notify the node that it should purge any content that is both expensive to fetch and to
- * retain in memory.
- *
- * @see [ASDisplayNode(Subclassing) clearFetchedData] and [ASDisplayNode(Subclassing) fetchData]
- */
-- (void)recursivelyClearFetchedData;
-
-/**
- * @abstract Calls -fetchData on the receiver and its subnode hierarchy.
- *
- * @discussion Fetches content from remote sources for the current node and all subnodes.
- *
- * @see [ASDisplayNode(Subclassing) fetchData] and [ASDisplayNode(Subclassing) clearFetchedData]
- */
-- (void)recursivelyFetchData;
-
-/**
- * @abstract Triggers a recursive call to fetchData when the node has an interfaceState of ASInterfaceStatePreload
- */
-- (void)setNeedsDataFetch;
-
 /**
  * @abstract Toggle displaying a placeholder over the node that covers content until the node and all subnodes are
  * displayed.