fix(cli): codegen jsSrcsDir subpath (#14530)

* fix(cli): codegenWindows file glob for subpaths

closes #14387

* Change files

Author: frankcalise

change/@react-native-windows-cli-7fd60dda-c73f-4b27-83e9-e2fec2b6c1de.json

@@ -0,0 +1,7 @@
+{
+  "type": "prerelease",
+  "comment": "fix(cli): codegenWindows file glob for subpaths",
+  "packageName": "@react-native-windows/cli",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

packages/@react-native-windows/cli/src/commands/codegenWindows/codegenWindows.ts

@@ -143,7 +143,10 @@ export class CodeGenWindows {
       'modulesWindows',
     ];
 
-    const jsRootPathRelative = path.relative(process.cwd(), jsRootDir);
+    const jsRootPathRelative = path
+      .relative(process.cwd(), jsRootDir)
+      .split(path.sep)
+      .join('/');
     const options: RnwCodeGenOptions = {
       files: [
         `${jsRootPathRelative}${