build: enable parallel project execution

- Add `org.gradle.parallel=true` to `gradle.properties` to allow Gradle to execute tasks in parallel for decoupled projects.

Author: rainxchzed

gradle.properties

@@ -6,6 +6,7 @@ kotlin.daemon.jvmargs=-Xmx3072M
 org.gradle.jvmargs=-Xmx4096M -Dfile.encoding=UTF-8
 org.gradle.configuration-cache=true
 org.gradle.caching=true
+org.gradle.parallel=true
 
 #Android
 android.nonTransitiveRClass=true