Handle walkThroughSnippet:/ and untitled:/ as dynamic files (#36722)

Handle walkThroughSnippet:/ and untitled:/ as dynamic files
Fixes #36681

src/server/scriptInfo.ts

@@ -273,6 +273,8 @@ namespace ts.server {
     /*@internal*/
     export function isDynamicFileName(fileName: NormalizedPath) {
         return fileName[0] === "^" ||
+            ((stringContains(fileName, "walkThroughSnippet:/") || stringContains(fileName, "untitled:/")) &&
+                getBaseFileName(fileName)[0] === "^") ||
             (stringContains(fileName, ":^") && !stringContains(fileName, directorySeparator));
     }