Report JSX-lowered files to the checker server as changed

The program the lowering compiles serves each file that has JSX at its
own path, with the JSX rewritten to calls (host.addVirtualFile). The
host reported such a path to the checker server as created whenever it
was not virtual yet. The files exist on disk and the server had already
read them for the program that checks them as written, so tsgo kept
their original text, and lowering met the JSX syntax: SC1090 "syntax
'JsxFragment' is not supported yet" in 6822, 6824 and 6825 under
SCRIPTC_CHECKER=tsgo, while tsc-ts reread the files.

A virtual file that replaces a file on disk is now reported as changed,
and both checkers give the same LLVM IR and diagnostics for the JSX
corpus programs.

packages/compiler/src/frontend/ts7/program-host.ts

@@ -192,7 +192,10 @@ export class Ts7Host {
     const key = tsgoPath(path);
     if (this.virtualFiles.get(key) === content) return;
     if (!this.virtualChanges.has(key))
-      this.virtualChanges.set(key, this.virtualFiles.has(key) ? "changed" : "created");
+      this.virtualChanges.set(
+        key,
+        this.virtualFiles.has(key) || trackedFileExists(path) ? "changed" : "created",
+      );
     this.virtualFiles.set(key, content);
   }