Update CodeGeneration to adapt changes in operator declaration

Author: StevenWong12

CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift

@@ -1189,24 +1189,14 @@ public let DECL_NODES: [Node] = [
     description: "A Swift `operator` declaration.",
     kind: "Decl",
     traits: [
-      "IdentifiedDecl",
-      "Attributed",
+      "IdentifiedDecl"
     ],
     children: [
       Child(
-        name: "Attributes",
-        kind: .collection(kind: "AttributeList", collectionElementName: "Attribute"),
-        nameForDiagnostics: "attributes",
-        description: "The attributes applied to the 'operator' declaration.",
-        isOptional: true
-      ),
-      Child(
-        name: "Modifiers",
-        kind: .collection(kind: "ModifierList", collectionElementName: "Modifier"),
-        nameForDiagnostics: "modifiers",
-        description: "The declaration modifiers applied to the 'operator' declaration.",
-        isOptional: true,
-        classification: "Attribute"
+        name: "OperatorModifier",
+        kind: .token(choices: [.keyword(text: "prefix"), .keyword(text: "postfix"), .keyword(text: "infix")]),
+        nameForDiagnostics: "modifier",
+        description: "The declaration modifier applied to the 'operator' declaration."
       ),
       Child(
         name: "OperatorKeyword",