Add ctrl.blog to UA whitelist

[da2x]

As the domain owner, I do solemnly swear not to negatively impact or discriminate against Brave users or misuse the ability to differentiate them from Chrome users. (I first asked for this in 2016-08.)

Domain ownership verification: https://www.ctrl.blog/.well-known/brave/user_agent_whitelist.txt.

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.
• Request 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

[bridiver]

@da2x we whitelist when necessary for site functionality. For instance, with adobe.com we have to expose the Brave UA for Flash downloads to work correctly (Chrome manages Flash downloads internally). I'm actually not sure why duckduckgo is on the list and I'd like to remove it if there isn't a specific requirement.

[da2x]

I want to use this to target Brave promotions to non-Brave users only. Kind of hard to do when I can’t tell Brave and Chrome apart.

[bridiver]

we've had discussions about ways for users to opt-in to identify themselves as Brave, but apart from other privacy related issues, it just isn't practical for us to maintain a list of sites who want to be able to identify Brave from the user agent string