added option to output test results to file

[mihaiplesa]

Close #1260

Part of https://github.com/brave/devops/issues/79

Added option to specify file for test output (results).

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Requested a security/privacy review as needed.

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions.

[mbacchi]

lgtm

[w0ts0n]

looks good.

[bsclifton]

@mihaiplesa added merged/0.56.x label; is this supposed to go into 0.55.x also? If so, let's merge and put the merged/0.55.x on it instead 😄 I also noticed the issue this fixes is still open?

[mihaiplesa]

Yes, I created the issue after the PR so it didn't get closed, should have been into 0.55.x as well.

[bsclifton]

@mihaiplesa ok great- I just merged with 0.55.x with e21fb29 😄

[mihaiplesa]

boom!