Add toString() to Any, fix all tests

#KT-4517 Fixed

idea/testData/checker/infos/Autocasts.kt

@@ -179,7 +179,7 @@ fun returnFunctionLiteral(<info>a</info>: Any?): Function0<Int> =
 fun merge<TYPO descr="Typo: In word 'Autocasts'">Autocasts</TYPO>(a: Any?) {
   if (a is String || a is Int) {
     a.<error descr="[UNRESOLVED_REFERENCE] Unresolved reference: compareTo">compareTo</error>("")
-    a.toString()
+    <info descr="Automatically cast to jet.Any"><info>a</info></info>.toString()
   }
   if (a is Int || a is String) {
     a.<error descr="[UNRESOLVED_REFERENCE] Unresolved reference: compareTo">compareTo</error>("")

idea/testData/codeInsight/overrideImplement/complexMultiOverride.kt.after

@@ -19,4 +19,7 @@ class C : Base<String, C, Unit>() {
         return super<Base>.hashCode()
     }
     override val method: (String?) -> String = ?
+    override fun toString(): String {
+        return super<Base>.toString()
+    }
 }

idea/testData/codeInsight/overrideImplement/inheritVisibilities.kt.after

@@ -30,4 +30,7 @@ class C : A(), B {
         super<A>.publicFun()
     }
     override val publicProperty: Int = 0
+    override fun toString(): String {
+        return super<A>.toString()
+    }
 }

idea/testData/codeInsight/overrideImplement/multiOverride.kt.after

@@ -17,4 +17,7 @@ class C : A {
     override fun hashCode(): Int {
         return super<A>.hashCode()
     }
+    override fun toString(): String {
+        return super<A>.toString()
+    }
 }

idea/testData/codeInsight/overrideImplement/overrideRespectCaretPosition.kt.after

@@ -16,6 +16,9 @@ class C : A() {
     override fun hashCode(): Int {
         return super<A>.hashCode()
     }
+    override fun toString(): String {
+        return super<A>.toString()
+    }
 
     /*
         Some another comment

idea/testData/resolve/builtins/toString.kt

@@ -1,2 +1,2 @@
 val x = 5.<ref>toString()
-//jet/Library.kt:toString
+//jet/Any.kt:toString