added specializing error "Variable initializer is redundant" for unused-vars analysis

compiler/testData/diagnostics/tests/BinaryCallsOnNullableValues.jet

@@ -11,7 +11,7 @@ class C() {
 }
 
 fun f(): Unit {
-  var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>x<!>: Int? = 1
+  var x: Int? = <!VARIABLE_WITH_REDUNDANT_INITIALIZER!>1<!>
   x = 1
   x <!UNSAFE_INFIX_CALL!>+<!> 1
   x <!UNSAFE_INFIX_CALL!>plus<!> 1

compiler/testData/diagnostics/tests/FunctionReturnTypes.jet

@@ -18,7 +18,7 @@ fun bbb() {
   return <!TYPE_MISMATCH!>1<!>
 }
 
-fun foo(expr: StringBuilder): Int {
+fun foo(<!UNUSED_PARAMETER!>expr<!>: StringBuilder): Int {
   val c = 'a'
   when(c) {
     0.chr => throw Exception("zero")
@@ -211,4 +211,4 @@ fun testFunctionLiterals() {
         object A {}
     }
 
-}
+}

compiler/testData/diagnostics/tests/UninitializedOrReassignedVariables.jet

@@ -16,7 +16,7 @@ fun t1(b : Boolean) {
     }
     doSmth(<!UNINITIALIZED_VARIABLE!>u<!>)
 
-    var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>r<!>: String
+    var r: String
     if (b) {
         r = "s"
     }

compiler/testData/diagnostics/tests/UnreachableCode.jet

@@ -137,7 +137,7 @@ fun tf() : Int {
   <!UNREACHABLE_CODE!>return 1<!>
 }
 
-fun failtest(a : Int) : Int {
+fun failtest(<!UNUSED_PARAMETER!>a<!> : Int) : Int {
   if (fail() || <!UNREACHABLE_CODE!>true<!>) {
 
   }

compiler/testData/diagnostics/tests/UnusedVariables.jet

@@ -1,7 +1,7 @@
 namespace unused_variables
 
 fun testSimpleCases() {
-    var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>i<!> = 2
+    var i = <!VARIABLE_WITH_REDUNDANT_INITIALIZER!>2<!>
     i = <!UNUSED_VALUE!>34<!>
     i = 34
     doSmth(i)
@@ -62,7 +62,7 @@ class MyTest() {
     }
 
     fun testIf() {
-        var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>a<!> : Any
+        var a : Any
         if (1 < 2) {
             a = 23
         }