Enable Explicit API mode warning in React Native Android (#40968)

Summary:
Pull Request resolved: #40968

Enable Explicit API mode warning to let product developers get notified of Explicit API checks (similar to deprecation mechanism). Explicit API mode will be enabled as strict in a future version

more details: https://kotlinlang.org/docs/whatsnew14.html#explicit-api-mode-for-library-authors

changelog: [Android][Changed] Enabling Explicit API warning, this will be changed as Strict in a future version

Reviewed By: cortinico

Differential Revision: D50295069

fbshipit-source-id: 41f7eb823ef8cfb4266dfa2d927f54c7dab9193a

packages/react-native/ReactAndroid/build.gradle

@@ -807,6 +807,8 @@ if (rootProject.name == "react-native-build-from-source") {
 
 kotlin {
     jvmToolchain(17)
+
+    explicitApi()
 }
 
 apply plugin: "org.jetbrains.kotlin.android"