Process script templates everywhere properly:

- add options to disable scripting plugin and standard script definition
- move standard definition adding logic into appropriate place
- fix logic of scripting plugin loading
- add standard script definition on the environment creation to
  ensure compatibility with all usages
- fix testdata
- some minor fixes

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -234,6 +234,9 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
     @Argument(value = "-Xdisable-default-scripting-plugin", description = "Do not enable scripting plugin by default")
     var disableDefaultScriptingPlugin: Boolean by FreezableVar(false)
 
+    @Argument(value = "-Xdisable-standard-script", description = "Disable standard kotlin script support")
+    var disableStandardScript: Boolean by FreezableVar(false)
+
     // Paths to output directories for friend modules.
     var friendPaths: Array<String>? by FreezableVar(null)