Add shields settings (uplift to 1.27.x)

[brave-builds]

Uplift of #9240
Resolves brave/brave-browser#16300
Resolves brave/brave-browser#16299

Pre-approval checklist:

• You have tested your change on Nightly.
• This contains text which needs to be translated.
  • There are more than 7 days before the release.
  • I've notified folks in #l10n on Slack that translations are needed.
• The PR milestones match the branch they are landing to.

Pre-merge checklist:

• You have checked CI and the builds, lint, and tests all pass or are not related to your PR.

Post-merge checklist:

• The associated issue milestone is set to the smallest version that the changes is landed on.

[kjozwiak]

test-browser failed on macOS as per https://ci.brave.com/job/pr-brave-browser-pr9240_add-shields-settings_1.27.x-macos/1/testReport/. However, these are known intermittent failures as per brave/brave-browser#13883 & brave/brave-browser#13884 and are unrelated to this specific PR.

macos-x64 / test-browser / RewardsContributionBrowserTest.SplitProcessOneTimeTip
macos-x64 / test-browser / RewardsContributionBrowserTest.SplitProcessorAutoContribution

[kjozwiak]

Uplift into 1.27.x approved after deliberating with @brave/uplift-approvers. QA has verified the PR on Nightly as per #9240 (comment).