Allow modifying iOS image cache limits (#33554)

Summary:
Allow modifying iOS image cache limits. Currently the image cache imposes some strict limits:

[NSCache.totalCostLimit](https://developer.apple.com/documentation/foundation/nscache/1407672-totalcostlimit?language=objc) of 20MB.
Single Image Size Limit of 2MB (bitmap size).

This may not be enough for applications that make heavy use of images. With this commit it is possible to fine tune them to the applications need.

This can be set for example in the App Delegate with:

```objc
RCTSetImageCacheLimits(4*1024*1024, 200*1024*1024);
```
This would increase the single image size limit to 4 MB and the total cost limit to 200 MB.

## Changelog

[iOS] [Added] - Allow modifying iOS image cache limits

Pull Request resolved: #33554

Test Plan: There is no easy way to test this except adding the above snippet and checking via break points that the new limits are used.

Reviewed By: cipolleschi

Differential Revision: D35485914

Pulled By: cortinico

fbshipit-source-id: 646cf7cab5ea5258d0d0d0bce6383317e27e4445

Libraries/Image/RCTImageCache.h

@@ -39,4 +39,7 @@
 @end
 
 @interface RCTImageCache : NSObject <RCTImageCache>
+
+RCT_EXTERN void RCTSetImageCacheLimits(NSUInteger maxCachableDecodedImageSizeInBytes, NSUInteger imageCacheTotalCostLimit);
+
 @end

Libraries/Image/RCTImageCache.m

@@ -18,7 +18,13 @@
 
 #import <React/RCTImageUtils.h>
 
-static const NSUInteger RCTMaxCachableDecodedImageSizeInBytes = 2097152; // 2 MB
+static NSUInteger RCTMaxCachableDecodedImageSizeInBytes = 2*1024*1024;
+static NSUInteger RCTImageCacheTotalCostLimit = 20*1024*1024;
+
+void RCTSetImageCacheLimits(NSUInteger maxCachableDecodedImageSizeInBytes, NSUInteger imageCacheTotalCostLimit) {
+  RCTMaxCachableDecodedImageSizeInBytes = maxCachableDecodedImageSizeInBytes;
+  RCTImageCacheTotalCostLimit = imageCacheTotalCostLimit;
+}
 
 static NSString *RCTCacheKeyForImage(NSString *imageTag, CGSize size, CGFloat scale,
                                      RCTResizeMode resizeMode)
@@ -38,7 +44,7 @@ - (instancetype)init
 {
   if (self = [super init]) {
     _decodedImageCache = [NSCache new];
-    _decodedImageCache.totalCostLimit = 20 * 1024 * 1024; // 20 MB
+    _decodedImageCache.totalCostLimit = RCTImageCacheTotalCostLimit;
     _cacheStaleTimes = [NSMutableDictionary new];
 
     [[NSNotificationCenter defaultCenter] addObserver:self