Switch to using Sync instead of Copy when assembling the scripts

Sync is slightly better because it effectively resets the output directory
before copying. That way, old files that shouldn't be included anymore are not
included (and avoids having to run ./gradlew clean).

Author: jthurne

build.gradle.kts

@@ -87,7 +87,7 @@ val copyThirdPartyComponents by tasks.registering(Sync::class) {
     exclude("build-scan-summary-$buildScanSummaryVersion.jar")
 }
 
-val unpackArgbash by tasks.registering(Copy::class) {
+val unpackArgbash by tasks.registering(Sync::class) {
     group = "argbash"
     description = "Unpacks Argbash."
     from(zipTree(argbash.singleFile)) {
@@ -117,7 +117,7 @@ val generateBashCliParsers by tasks.registering(ApplyArgbash::class) {
     })
 }
 
-val copyGradleScripts by tasks.registering(Copy::class) {
+val copyGradleScripts by tasks.registering(Sync::class) {
     group = "build"
     description = "Copies the Gradle source and the generated scripts to the output directory."
 
@@ -169,7 +169,7 @@ val copyGradleScripts by tasks.registering(Copy::class) {
     into(layout.buildDirectory.dir("scripts/gradle"))
 }
 
-val copyMavenScripts by tasks.registering(Copy::class) {
+val copyMavenScripts by tasks.registering(Sync::class) {
     group = "build"
     description = "Copies the Maven source and the generated scripts to the output directory."