Added diagnostic error when in function declaration name was omitted

idea/testData/quickfix/autoImports/beforeNamelessFunction.kt

@@ -1,5 +1,6 @@
 // "class com.intellij.codeInsight.daemon.impl.quickfix.ImportClassFixBase" "false"
 // ERROR: Unresolved reference: TTTTT
+// ERROR: Function declaration must have a name
 
 fun () {
     val tttt : TTTTT = null

idea/testData/quickfix/typeMismatch/afterChangeReturnTypeWhenFunctionNameIsMissing.kt

@@ -1,4 +1,5 @@
 // "Remove explicitly specified function return type" "true"
+// ERROR: Function declaration must have a name
 fun () {
     return<caret>
 }

idea/testData/quickfix/typeMismatch/beforeChangeReturnTypeWhenFunctionNameIsMissing.kt

@@ -1,4 +1,5 @@
 // "Remove explicitly specified function return type" "true"
+// ERROR: Function declaration must have a name
 fun (): Int {
     return<caret>
 }