fix(react-native): add prefabPublishing to hermes-engine for build-from-source

PR #54707 removed `prefabPublishing = true` from hermes-engine when
switching to prebuilt Hermes by default. This broke build-from-source
because AGP no longer generates the CMake config file needed by
`find_package(hermes-engine)` in ReactAndroid's native build.

Adding `prefabPublishing = true` back restores the CMake config
generation and proper Gradle task ordering.

The same PR also disables all hermes tasks when not building from
source - which will make the CI work correctly - ie. not build hermes
from source when not needed.

Author: chrfalch

packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts

@@ -421,7 +421,10 @@ android {
     java.srcDirs("$hermesDir/lib/Platform/Intl/java", "$hermesDir/lib/Platform/Unicode/java")
   }
 
-  buildFeatures { prefab = true }
+  buildFeatures {
+    prefab = true
+    prefabPublishing = true
+  }
 
   dependencies {
     implementation(libs.fbjni)