Youtube channels with special characters in name now appear correctly

[jasonrsadler]

Fixes brave/brave-browser#2028

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.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone

Test Plan:

1. Open Brave and enable Rewards
2. Visit youtube publisher with ampersand in name
   (https://www.youtube.com/channel/UC5v8uRCMdzHXgEOZC4rtbXg)
   (https://www.youtube.com/channel/UCp3QO2qJy2hvIBrRoWSaCRw)

(& seems to be the only character that youtube performs JSON encoding on, however, all encoding is handled through this PR)

3. Open panel and make sure publisher name is correct

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

[NejcZdovc]

@jasonrsadler please rebase

[jasonrsadler]

Done