Makes HermesRuntimeImpl::isArray proxy-compatible

When using hermes engine, [`dynamicFromValue` in React Native](https://github.com/facebook/hermes/blob/main/API/jsi/jsi/JSIDynamic.cpp#L166) calls `isArray` here to check if the input object is an array.

Consider this piece of code:
```js
const list = ['a', 'b', 'c', 'd'];
const proxyed_list = new Proxy(list, {});
```

The `proxyed_list` behaves exactly the same as list in Javascript. But when been passed to native and converted to `folly::dynamic` by `dynamicFromValue`, `proxyed_list` will be converted to `{"0": "a", "1": "b", "2": "c", "3": "d"}` but not the expected `["a", "b", "c", "d"]`.

This patch implements similar routines in commit [26840ed](26840ed#diff-059b8f2fcb0235b35582efc591e065bd8caa898c3ea2ef2a3e453bff97584e4dR1575) and makes `isArray` proxy-compatible.

API/hermes/hermes.cpp

@@ -29,6 +29,8 @@
 #include "hermes/VM/JSArrayBuffer.h"
 #include "hermes/VM/JSLib.h"
 #include "hermes/VM/JSLib/RuntimeJSONUtils.h"
+#include "hermes/VM/JSObject.h"
+#include "hermes/VM/JSProxy.h"
 #include "hermes/VM/NativeState.h"
 #include "hermes/VM/Operations.h"
 #include "hermes/VM/Profiler/CodeCoverageProfiler.h"
@@ -1996,7 +1998,20 @@ void HermesRuntimeImpl::setPropertyValue(
 }
 
 bool HermesRuntimeImpl::isArray(const jsi::Object &obj) const {
-  return vm::vmisa<vm::JSArray>(phv(obj));
+  vm::JSObject *jsobj = static_cast<vm::JSObject *>(phv(obj).getPointer());
+  while (true) {
+    if (vm::vmisa<vm::JSArray>(jsobj)) {
+      return true;
+    }
+    if (LLVM_LIKELY(!jsobj->isProxyObject())) {
+      return false;
+    }
+    if (vm::JSProxy::isRevoked(jsobj, runtime_)) {
+      return false;
+    }
+    jsobj = vm::JSProxy::getTarget(jsobj, runtime_).get();
+    assert(jsobj && "target of non-revoked Proxy is null");
+  }
 }
 
 bool HermesRuntimeImpl::isArrayBuffer(const jsi::Object &obj) const {