KT-759 Filter keywords auto completion according to context

idea/testData/completion/keywords/InClassScope.kt

@@ -0,0 +1,54 @@
+class TestClass {
+    <caret>
+}
+
+// EXIST:  abstract
+// ABSENT: annotation
+// ABSENT: as
+// ABSENT: break
+// ABSENT: by
+// ABSENT: catch
+// EXIST:  class
+// ABSENT: continue
+// ABSENT: default
+// ABSENT: do
+// ABSENT: else
+// EXIST:  enum
+// ABSENT: false
+// EXIST:  final
+// ABSENT: finally
+// ABSENT: for
+// EXIST:  fun
+// EXIST:  get
+// ABSENT: if
+// ABSENT: import
+// ABSENT: in
+// EXIST:  inline
+// EXIST:  internal
+// ABSENT: is
+// ABSENT: null
+// ABSENT: object
+// EXIST:  open
+// ABSENT: out
+// EXIST:  override
+// ABSENT: package
+// EXIST:  private
+// EXIST:  protected
+// EXIST:  public
+// ABSENT: ref
+// ABSENT: return
+// EXIST:  set
+// ABSENT: super
+// ABSENT: This
+// ABSENT: this
+// ABSENT: throw
+// EXIST:  trait
+// ABSENT: true
+// ABSENT: try
+// EXIST:  type
+// EXIST:  val
+// EXIST:  var
+// ABSENT: vararg
+// ABSENT: when
+// ABSENT: where
+// ABSENT: while