fix: Use same implementation for performance.now() on iOS and Android (#32695)

Summary:
I've noticed that the `performance.now()` implementations differ on iOS and Android.

iOS:
```objc
PerformanceNow iosPerformanceNowBinder = []() {
  // CACurrentMediaTime() returns the current absolute time, in seconds
  return CACurrentMediaTime() * 1000;
};
```
Android:
```c++
double reactAndroidNativePerformanceNowHook() {
  auto time = std::chrono::steady_clock::now();
  auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(
                      time.time_since_epoch())
                      .count();

  constexpr double NANOSECONDS_IN_MILLISECOND = 1000000.0;

  return duration / NANOSECONDS_IN_MILLISECOND;
}
```

For consistency, I thought why not just use the same implementation on both iOS and Android.

It also seems more logical to use Chrono on iOS, since it has nanosecond precision and we just multiply it to milliseconds, whereas `CACurrentMediaTime` multiplies to seconds, and we divide it down to milliseconds again.

## Changelog

(internal change only)

Pull Request resolved: https://github.com/facebook/react-native/pull/32695

Test Plan:
Run on iOS and Android:

```ts
const now = global.performance.now()
console.log(`${Platform.OS}: ${now}`)
```

Reviewed By: feedthejim

Differential Revision: D32793838

Pulled By: ShikaSD

fbshipit-source-id: e7967780be95956a75a3a3757311af0077976d23

React/CxxBridge/RCTJSIExecutorRuntimeInstaller.mm

@@ -8,6 +8,7 @@
 #include "RCTJSIExecutorRuntimeInstaller.h"
 
 #import <React/RCTLog.h>
+#include <chrono>
 
 namespace facebook {
 namespace react {
@@ -21,8 +22,8 @@ JSIExecutor::RuntimeInstaller RCTJSIExecutorRuntimeInstaller(JSIExecutor::Runtim
     bindNativeLogger(runtime, iosLoggingBinder);
 
     PerformanceNow iosPerformanceNowBinder = []() {
-      // CACurrentMediaTime() returns the current absolute time, in seconds
-      return CACurrentMediaTime() * 1000;
+      auto time = std::chrono::system_clock::now().time_since_epoch();
+      return std::chrono::duration_cast<std::chrono::milliseconds>(time).count();
     };
     bindNativePerformanceNow(runtime, iosPerformanceNowBinder);
 

ReactAndroid/src/main/jni/react/jni/NativeTime.cpp

@@ -12,14 +12,8 @@ namespace facebook {
 namespace react {
 
 double reactAndroidNativePerformanceNowHook() {
-  auto time = std::chrono::steady_clock::now();
-  auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(
-                      time.time_since_epoch())
-                      .count();
-
-  constexpr double NANOSECONDS_IN_MILLISECOND = 1000000.0;
-
-  return duration / NANOSECONDS_IN_MILLISECOND;
+  auto time = std::chrono::system_clock::now().time_since_epoch();
+  return std::chrono::duration_cast<std::chrono::milliseconds>(time).count();
 }
 
 } // namespace react