Add test for ninja clean
Add test for ninja clean

This makes sure that all output files are listed in the typescript.gni
Otherwise, `ninja -t clean` would leave files behind.

R=993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org

Bug: 1064287
Change-Id: I980b7d4ec71e1b75c37c17b580fc8202255b950c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2119548
Commit-Queue: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Commit-Queue: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>
Auto-Submit: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Reviewed-by: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend