JavaScript: Skip npmPublish when npmBuild is restored from cache

When npmBuild is restored from the build cache (no JS source changes),
version.txt retains the timestamp from the original build, causing npm
to reject the publish with a 403 since that version already exists.

Adding onlyIf { npmBuild.get().state.didWork } to npmPublish for
snapshot builds so we skip publishing when nothing actually changed.

Author: knutwannheden

rewrite-javascript/build.gradle.kts

@@ -227,6 +227,11 @@ val npmPublish = tasks.register<NpmTask>("npmPublish") {
     args = provider { listOf("publish", npmPack.get().archiveFile.get().asFile.absolutePath) }
     if (!project.hasProperty("releasing")) {
         args.addAll("--tag", "next")
+        // Skip publishing when nothing changed in the JavaScript implementation.
+        // When npmBuild is restored from the build cache, version.txt retains the
+        // timestamp from the original build, causing a conflict with the previously
+        // published version on npmjs.
+        onlyIf { npmBuild.get().state.didWork }
     }
 
     workingDir.set(file("rewrite"))