Preserve the old function name for removeStorageDataForKey in Swift. (#…

…24627)

By default, this is getting renamed to "removeData(forKey:)" in Swift, because
the protocol is now called MTRStorage and for some reason the Swift name mapping
cares about that for just this one function.

This breaks existing consumers.  Use NS_SWIFT_NAME to preserve the existing
name.

src/darwin/Framework/CHIP/MTRStorage.h

@@ -48,7 +48,7 @@ MTR_NEWLY_AVAILABLE
  * Delete the key and corresponding data.  Returns YES if the key was present,
  * NO if the key was not present.
  */
-- (BOOL)removeStorageDataForKey:(NSString *)key;
+- (BOOL)removeStorageDataForKey:(NSString *)key NS_SWIFT_NAME(removeStorageData(forKey:));
 
 @end