Exclude keywords from completion if the corresponding feature is unsupported by the language level selected for the module

idea/idea-completion/testData/keywords/AfterClasses_LangLevel10.kt

@@ -0,0 +1,37 @@
+class A {
+    fun foo() {
+        bar()
+    }
+}
+
+class B {
+    fun bar() {
+        foo()
+    }
+}
+
+<caret>
+
+// EXIST:  abstract
+// EXIST:  class
+// EXIST:  enum class
+// EXIST:  final
+// EXIST:  fun
+// EXIST:  internal
+// EXIST:  object
+// EXIST:  open
+// EXIST:  private
+// EXIST:  public
+// EXIST:  interface
+// EXIST:  val
+// EXIST:  var
+// EXIST:  operator
+// EXIST:  infix
+// EXIST:  sealed
+// EXIST:  data
+// EXIST:  inline
+// EXIST:  tailrec
+// EXIST:  external
+// EXIST:  annotation class
+// EXIST:  const
+// NOTHING_ELSE