KJS: allow to use packages with names starting with "kotlin" only if the -Xallow-kotlin-package command line option is specified

#KT-14668 Fixed

compiler/testData/cli/js/jsExtraHelp.out

@@ -2,6 +2,7 @@ Usage: kotlinc-js <options> <source files>
 where advanced options include:
   -Xno-inline                Disable method inlining
   -Xrepeat <count>           Repeat compilation (for performance analysis)
+  -Xallow-kotlin-package     Allow compiling code in package 'kotlin'
   -Xplugin <path>            Load plugins from the given classpath
   -Xmulti-platform           Enable experimental language support for multi-platform projects
   -Xno-check-impl            Do not check presence of 'impl' modifier in multi-platform projects

compiler/testData/cli/js/kotlinPackage.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/../kotlinPackage.kt
+-no-stdlib
+-output
+$TEMP_DIR$/out.js

compiler/testData/cli/js/kotlinPackage.out

@@ -0,0 +1,4 @@
+compiler/testData/cli/kotlinPackage.kt:1:1: error: only the Kotlin standard library is allowed to use the 'kotlin' package
+package kotlin.mylibrary
+^
+COMPILATION_ERROR