Override completion right after override modifier

#KT-25312 Fixed

idea/idea-completion/testData/handlers/basic/override/kt25312.kt

@@ -0,0 +1,8 @@
+interface Interface {
+    fun funA()
+}
+
+expect class SClass : Interface { // there is no error highlighting about unimplemented members, see KT-25044
+    override fu<caret>
+}
+// ELEMENT_TEXT: "override fun funA() {...}"

idea/idea-completion/testData/handlers/basic/override/kt25312.kt.after

@@ -0,0 +1,8 @@
+interface Interface {
+    fun funA()
+}
+
+expect class SClass : Interface { // there is no error highlighting about unimplemented members, see KT-25044
+    override fun funA()<caret>
+}
+// ELEMENT_TEXT: "override fun funA() {...}"