JS stdlib api test: various changes

- Setting -Doverwrite.output=true updates gold data
- Big packages don't get split into chunks
- Unique lines in the API are marked with /*∆*/ and diff test is removed
- Annotations on separate lines and other dump format tweaks
- Test data moved to libraries/stdlib/api/
- Minor visibility fix to Enum members

js/js.tests/build.gradle.kts

@@ -131,6 +131,8 @@ fun Test.setUpBoxTests() {
         systemProperty("kotlin.ant.launcher.class", "org.apache.tools.ant.Main")
     }
 
+    systemProperty("overwrite.output", findProperty("overwrite.output") ?: "false")
+
     val prefixForPpropertiesToForward = "fd."
     for ((key, value) in properties) {
         if (key.startsWith(prefixForPpropertiesToForward)) {