OSS Gradle: increase JVM heap size

Summary:
Increasing memory for building RNTester in Gradle.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D23078460

fbshipit-source-id: 733246a44bd88532796cd40be59aeee366db8ab0

RNTester/android/app/build.gradle

@@ -122,6 +122,10 @@ android {
         targetCompatibility JavaVersion.VERSION_1_8
     }
 
+    dexOptions {
+       javaMaxHeapSize "4g"
+    }
+
     flavorDimensions "vm"
     productFlavors {
         hermes {

gradle.properties

@@ -0,0 +1,4 @@
+org.gradle.configureondemand=true
+org.gradle.daemon=true
+org.gradle.jvmargs=-Xmx4g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
+org.gradle.parallel=true