Show the QR code in Brave Rewards (brave://rewards)

[bsclifton]

Fixes brave/brave-browser#13159

---

Revert "Merge pull request #7350 from brave/bsc-remove-qr-code"

This reverts commit 858ca76, reversing
changes made to ba5983c.

Resolves

Submitter Checklist:

• There is a ticket for my issue.
• Used Github auto-closing keywords in the commit message.
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed).
• Requested a security/privacy review as needed.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[emerick]

LGTM

[bsclifton]

Partially blocked on brave-intl/bat-go#611

[kjozwiak]

Restarting macOS via https://ci.brave.com/job/pr-brave-browser-bsc-show-qr-code-macos/2/ as build failed as per https://ci.brave.com/job/pr-brave-browser-bsc-show-qr-code-macos/1/execution/node/207/log/.

02:42:05  FAILED: gen/chrome/browser/resources/extensions/extensions.rollup.js gen/chrome/browser/resources/extensions/build_manifest.json 

[bsclifton]

iOS failing is not related to this; created brave/brave-browser#13210 to cover that

[kjozwiak]

awesome, thanks for getting this PR in good shape @bsclifton 👍 As soon as we're done with https://github.com/brave/internal/issues/739, we'll get it merged.