Update the template to load the correct JS engine at runtime. (#35095)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/35095

This change will make sure that we load the correct JS engine at runtime,
by using the BuildConfig flag that RNGP sets for us.

This will solve a lot of noise in adb logcat for users seeing
stacktraces mentioning failing to load `jscexecutor` library.

This is also a breaking change, but as the API was not widely used nor
advertised in the template, we should be fine by just mentioning this in the release notes.

Changelog:
[Android] [Changed] - Update the template to load the correct JS engine at runtime

Reviewed By: cipolleschi

Differential Revision: D40710597

fbshipit-source-id: d59a7a52b22a9bf273ea89094c6620c3ecf6eb00

ReactAndroid/src/main/java/com/facebook/react/JSEngineResolutionAlgorithm.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react;
+
+/**
+ * An enum that specifies the algorithm to use when loading theJS Engine. {@link #JSC} will load
+ * JavaScriptCore first and fail if it is not available. {@link #HERMES} will load Hermes first and
+ * fail if it is not available.
+ */
+public enum JSEngineResolutionAlgorithm {
+  JSC,
+  HERMES
+}