Fix tests: "infix modifier required" and "operator modifier required" errors

compiler/testData/diagnostics/tests/incompleteCode/plusOnTheRight.kt

@@ -2,9 +2,9 @@
 package a
 
 class MyClass1 {
-    public operator fun plus() {}
+    public operator fun unaryPlus() {}
 }
 
 fun main(arg: MyClass1) {
-    arg<!TOO_MANY_ARGUMENTS!>+<!><!SYNTAX!><!>
+    arg<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>+<!><!SYNTAX!><!>
 }

compiler/testData/diagnostics/tests/incompleteCode/plusOnTheRight.txt

@@ -7,7 +7,7 @@ package a {
         public constructor MyClass1()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-        public final operator fun plus(): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+        public final operator fun unaryPlus(): kotlin.Unit
     }
 }

compiler/testData/diagnostics/tests/redeclarations/ScriptAndClassConflict.txt

@@ -2,13 +2,6 @@ package
 
 package test {
 
-    public final class A {
-        public constructor A()
-        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-    }
-
     public final class A {
         public constructor A()
         public final val x: kotlin.Int = 1
@@ -24,6 +17,13 @@ package test {
         }
     }
 
+    public final class A {
+        public constructor A()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
     public final class F1 {
         public constructor F1()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean

compiler/testData/diagnostics/tests/scopes/kt250.617.10.kt

@@ -21,7 +21,7 @@ abstract class Tag(val name : String) {
 }
 
 abstract class TagWithText(name : String) : Tag(name) {
-  fun String.plus() {
+  operator fun String.unaryPlus() {
     children.add(TextElement(this))
   }
 }

compiler/testData/diagnostics/tests/scopes/kt250.617.10.txt

@@ -26,7 +26,7 @@ package kt_250_617_10 {
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-        public final override /*1*/ /*fake_override*/ fun kotlin.String.plus(): kotlin.Unit
+        public final override /*1*/ /*fake_override*/ fun kotlin.String.unaryPlus(): kotlin.Unit
     }
 
     public final class Body1 : kt_250_617_10.BodyTag {
@@ -37,7 +37,7 @@ package kt_250_617_10 {
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-        public final override /*1*/ /*fake_override*/ fun kotlin.String.plus(): kotlin.Unit
+        public final override /*1*/ /*fake_override*/ fun kotlin.String.unaryPlus(): kotlin.Unit
     }
 
     public open class BodyTag : kt_250_617_10.TagWithText {
@@ -48,7 +48,7 @@ package kt_250_617_10 {
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-        public final override /*1*/ /*fake_override*/ fun kotlin.String.plus(): kotlin.Unit
+        public final override /*1*/ /*fake_override*/ fun kotlin.String.unaryPlus(): kotlin.Unit
     }
 
     public open class Element {
@@ -92,7 +92,7 @@ package kt_250_617_10 {
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-        public final fun kotlin.String.plus(): kotlin.Unit
+        public final operator fun kotlin.String.unaryPlus(): kotlin.Unit
     }
 
     public final class TextElement : kt_250_617_10.Element {