fix: Correctly resolve classes with FindClass(..) (#34533)

Summary:
`JNIEnv`'s `FindClass(..)` function takes the classes in the standard
`foo/bar/Baz` class specification (unless they're special, like arrays).
Specifying them with `Lfoo/bar/Baz;` results in a
`ClassNotFoundException` being raised -- which is especially unhelpful
when intending to re-throw an exception.

The docs for `JNIEnv#FindClass(..)` can be found [here][jnienv].

[jnienv]:
  https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html#:~:text=The%20name%20argument,java/lang/String%22

## Changelog

[Android] [Fixed] - Correctly resolve classes with FindClass(..)

X-link: https://github.com/facebook/react-native/pull/34533

Reviewed By: amir-shalem

Differential Revision: D39133326

Pulled By: jacdebug

fbshipit-source-id: 86283b7d21aed49ed0e9027b2aef85f0108cdf9a

java/jni/YogaJniException.cpp

@@ -15,7 +15,7 @@ namespace yoga {
 namespace vanillajni {
 
 YogaJniException::YogaJniException() {
-  jclass cl = getCurrentEnv()->FindClass("Ljava/lang/RuntimeException;");
+  jclass cl = getCurrentEnv()->FindClass("java/lang/RuntimeException");
   static const jmethodID methodId = facebook::yoga::vanillajni::getMethodId(
       getCurrentEnv(), cl, "<init>", "()V");
   auto throwable = getCurrentEnv()->NewObject(cl, methodId);