Enable Gradle caching and parallel execution

Update gradle.properties to uncomment and enable Gradle build caching and parallel execution for improved build performance.

Author: hsz

gradle.properties

@@ -28,8 +28,8 @@ testGradleArguments=
 testIntelliJVersion=2021.2.4
 testMarkdownPluginVersion=212.5457.16
 
-#org.gradle.caching=true
-#org.gradle.parallel=true
+org.gradle.caching=true
+org.gradle.parallel=true
 
 # Dokka is incompatible with the configuration cache https://github.com/Kotlin/dokka/issues/1217
 #org.gradle.unsafe.configuration-cache=true