Convert main task creating helper to lazy API, refactor accordingly

libraries/tools/kotlin-main-kts/build.gradle.kts

@@ -73,24 +73,24 @@ val proguard by task<ProGuardTask> {
     dependsOn(packJar)
     configuration("main-kts.pro")
 
-    injars(mapOf("filter" to "!META-INF/versions/**"), packJar.outputs.files)
+    injars(mapOf("filter" to "!META-INF/versions/**"), packJar.get().outputs.files)
 
     val outputJar = fileFrom(buildDir, "libs", "$jarBaseName-$version-after-proguard.jar")
 
     outjars(outputJar)
 
-    inputs.files(packJar.outputs.files.singleFile)
+    inputs.files(packJar.get().outputs.files.singleFile)
     outputs.file(outputJar)
 
     libraryjars(mapOf("filter" to "!META-INF/versions/**"), proguardLibraryJars)
 }
 
-val resultJar = tasks.register<Jar>("resultJar") {
+val resultJar by task<Jar> {
     val pack = if (kotlinBuildProperties.proguard) proguard else packJar
     dependsOn(pack)
     setupPublicJar(jarBaseName)
     from {
-        zipTree(pack.outputs.files.singleFile)
+        zipTree(pack.get().outputs.files.singleFile)
     }
 }