Correct As from Punctuation to Keyword in SymbolDisplay. (#25719)

Merging on behalf of @AdamSpeight2008 
Thanks for the contribution

src/Compilers/VisualBasic/Portable/SymbolDisplay/SymbolDisplayVisitor.Types.vb

@@ -370,7 +370,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 If Not element.IsImplicitlyDeclared Then
                     builder.Add(CreatePart(SymbolDisplayPartKind.FieldName, symbol, element.Name, noEscaping:=False))
                     AddSpace()
-                    AddPunctuation(SyntaxKind.AsKeyword)
+                    AddKeyword(SyntaxKind.AsKeyword)
                     AddSpace()
                 End If
 

src/Compilers/VisualBasic/Test/Symbol/SymbolDisplay/SymbolDisplayTests.vb

@@ -4728,14 +4728,14 @@ End Class
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.StructName,
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.ClassName,
                 SymbolDisplayPartKind.Punctuation)
@@ -4808,14 +4808,14 @@ End Class
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Punctuation)
@@ -4899,14 +4899,14 @@ End Class"
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Punctuation,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.FieldName,
                 SymbolDisplayPartKind.Space,
-                SymbolDisplayPartKind.Punctuation,
+                SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Space,
                 SymbolDisplayPartKind.Keyword,
                 SymbolDisplayPartKind.Punctuation)