Custom client for ddg.

[iccub]

Ref: internal#648

Summary of Changes

This pull request fixes issue #1478

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()

Test Plan:

• Verify iOS device is in the United States region

• Launch Brave and use DDG as the default search engine (can go into private mode to make this easier)

• Perform a search

• Verify the URL contains t=brave in the URL bar (may need to long-press "copy" and paste somewhere else to see full URL)

• Change iOS device region to New Zealand

• Back in Brave perform another DDG search

• verify URL contains t=braveed (noticed additional ed)

• That's it. Cheers 🌮

Screenshots:

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • release-notes/(include|exclude)
  • bug / enhancement
• Necessary security reviews have taken place.
• Adequate unit test coverage exists to prevent regressions.
• Adequate test plan exists for QA to validate (if applicable).
• Issue is assigned to a milestone (should happen at merge time).

[jhreis]

I think some of the behaviors here aren't quite right, but that is mostly due to product requirements not being clear. I'm blocking this for now, and bumping the ticket out of the current milestone.

[jhreis]

Will leave more formal review once we identify the exact, expected behavior.

[iccub]

This should be ready for review @jhreis

[jhreis]

I don't think we should move this, if we ran into some weird issue, it could end up duplicating all default favorites. I think that is the only real thing that uses the isFirstLaunch bool.

[jhreis]

Very nice! 😄

[jumde]

lgtm