Setup spacing rules for secondary constructors

#KT-6968 Fixed

idea/testData/formatter/SpaceAroundExtendColonInSecondaryCtr.after.kt

@@ -0,0 +1,16 @@
+class A {
+    constructor() {
+    }
+
+    constructor() :this() {
+    }
+
+    constructor() :super() {
+    }
+
+    constructor() :super() {
+    }
+}
+
+// SET_TRUE: SPACE_BEFORE_EXTEND_COLON
+// SET_FALSE: SPACE_AFTER_EXTEND_COLON