Fix skewX/skewY/perspective/matrix on iOS (#28863)

Summary:
See discussion on c681959#commitcomment-38965326

This PR fixes skewX/skewY/perspective/matrix on iOS as seen on this video: https://youtu.be/LK9iOKk62nw?t=115

## Changelog

[iOS] [Fixed] Bug with skewX/skewY/perspective/matrix transforms.
Pull Request resolved: #28863

Test Plan:
Try that the following transform as been fixed on iOS

```tsx
<View
  style={{ transform: [{ rotateZ: Math.PI / 2}, { skewX: Math.PI/6 }] }}
/>
```

Differential Revision: D21493022

Pulled By: shergin

fbshipit-source-id: 4bf3550941e8acd8fdb87fe1143b21639c95b059

Author: wcandillon

React/Views/RCTConvert+Transform.m

@@ -65,6 +65,7 @@ + (CATransform3D)CATransform3D:(id)json
 
   CGFloat zeroScaleThreshold = FLT_EPSILON;
 
+  CATransform3D next;
   for (NSDictionary *transformConfig in (NSArray<NSDictionary *> *)json) {
     if (transformConfig.count != 1) {
       RCTLogConvertError(json, @"a CATransform3D. You must specify exactly one property per transform object.");
@@ -74,10 +75,13 @@ + (CATransform3D)CATransform3D:(id)json
     id value = transformConfig[property];
 
     if ([property isEqualToString:@"matrix"]) {
-      transform = [self CATransform3DFromMatrix:value];
+      next = [self CATransform3DFromMatrix:value];
+      transform = CATransform3DConcat(next, transform);
 
     } else if ([property isEqualToString:@"perspective"]) {
-      transform.m34 = -1 / [value floatValue];
+      next = CATransform3DIdentity;
+      next.m34 = -1 / [value floatValue];
+      transform = CATransform3DConcat(next, transform);
 
     } else if ([property isEqualToString:@"rotateX"]) {
       CGFloat rotate = [self convertToRadians:value];
@@ -123,11 +127,15 @@ + (CATransform3D)CATransform3D:(id)json
 
     } else if ([property isEqualToString:@"skewX"]) {
       CGFloat skew = [self convertToRadians:value];
-      transform.m21 = tanf(skew);
+      next = CATransform3DIdentity;
+      next.m21 = tanf(skew);
+      transform = CATransform3DConcat(next, transform);
 
     } else if ([property isEqualToString:@"skewY"]) {
       CGFloat skew = [self convertToRadians:value];
-      transform.m12 = tanf(skew);
+      next = CATransform3DIdentity;
+      next.m12 = tanf(skew);
+      transform = CATransform3DConcat(next, transform);
 
     } else {
       RCTLogError(@"Unsupported transform type for a CATransform3D: %@.", property);