Handle untitled files from vscode which are of format: untitled:^Untitled-1 (#36240)

* Test for #36200

* Handle dynamic files by vscode
Fixes #36200

src/server/editorServices.ts

@@ -1304,7 +1304,7 @@ namespace ts.server {
             // Closing file should trigger re-reading the file content from disk. This is
             // because the user may chose to discard the buffer content before saving
             // to the disk, and the server's version of the file can be out of sync.
-            const fileExists = this.host.fileExists(info.fileName);
+            const fileExists = info.isDynamic ? false : this.host.fileExists(info.fileName);
             info.close(fileExists);
             this.stopWatchingConfigFilesForClosedScriptInfo(info);
 

src/server/scriptInfo.ts

@@ -272,7 +272,8 @@ namespace ts.server {
 
     /*@internal*/
     export function isDynamicFileName(fileName: NormalizedPath) {
-        return fileName[0] === "^";
+        return fileName[0] === "^" ||
+            (stringContains(fileName, ":^") && !stringContains(fileName, directorySeparator));
     }
 
     /*@internal*/