Parameterise test runs
Parameterise test runs

This CL adds two flags to our run_test_suite helper:

* --cwd to set the current working directory to use as a base to find
  tests
* --node_modules-path, which sets NODE_PATH to the given value. This can
  be used to aid Node in resolving require statements if node_modules
  aren't in the local node_modules folder.

Bug: none
Change-Id: I6c7f83d028d3ad689b61642aa9a5e51177c0628d
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2718296
Commit-Queue: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>
Commit-Queue: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>
Auto-Submit: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>
Reviewed-by: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>

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