Report initializer block-related diagnostic on 'init' keyword

idea/testData/checker/AnonymousInitializers.kt

@@ -1,13 +1,13 @@
 interface NoC {
-  <error>init {
+  <error>init</error> {
 
-  }</error>
+  }
 
   val a : Int get() = 1
 
-  <error>init {
+  <error>init</error> {
 
-  }</error>
+  }
 }
 
 class WithC() {
@@ -24,4 +24,4 @@ class WithC() {
     val <warning>zz</warning> = x
   }
 
-}
+}

idea/testData/checker/regression/InitializerInInterface.kt

@@ -1,6 +1,6 @@
 interface I {
-    <error>init {
+    <error>init</error> {
         val c = 1
-        val g = c
-    }</error>
-}
+        val <warning>g</warning> = c
+    }
+}