Add rel='noopener' to all external links

[voldemortensen]

To avoid tab-nabbing attacks, all external links with
target='_blank' must have rel='noopener'

Fix #9743

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).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
  (I couldn't find a list of people to tag, although I did read the pull request process page.)

Test Plan:
See #10290 (comment)

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[voldemortensen]

Hmm.. I'll take a look at the failing tests.

[luixxiul]

@voldemortensen there are some failing tests and you don't have to try to fix them unless you introduced new ones with your PR.

[bsclifton]

Adding @darkdh for review too 😄

[diracdeltas]

thanks for submitting this!

[voldemortensen]

My pleasure! I'll definitely be contributing more. I love the ideas around this browser.

[bsclifton]

Awesome, thanks for the contribution @voldemortensen! 😄 As a follow up, would you be able to add some QA steps (ex: which screens to visit)?

[voldemortensen]

Absolutely

[voldemortensen]

QA steps:

Visit a new tab

• Check the photographers link in bottom left corner.

Visit the torrent viewer page

• Check the link to webtorrent.io.
• View a torrent and check the link to download the file.

Visit the about Brave page

• Check the Brave release notes link
• Check the link to the github commit revision

Visit the Sync page

• Check the question mark link that goes to github

Visit the Payments tab

• Check link to each partner
• Check both links to the Brave FAQ page

Activate payments

• Check payment history links

Visit Bitcoin page

• Check links to iOS and Android apps
• Check exchange link
• Check ledger data links

(I think I got everything)

[luixxiul]

@voldemortensen perfect! thanks for the steps :-)

[darkdh]

++