Implement NTP Custom homepage ("super referral") (uplift to 1.8.x)

[brave-builds]

Uplift of #4975
Uplift of #4866
Uplift of #5290

Fixes brave/brave-browser#8540
Fixes brave/brave-browser#8218
Fixes brave/brave-browser#9329

Approved, please ensure that before merging:

• You have checked CI and the builds, lint, and tests all pass or are not related to your PR.
• You have tested your change on Nightly.
• The PR milestones match the branch they are landing to.

After you merge:

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

[bsclifton]

I think there is an Android error here, possibly due to merge conflict resolution that I did:
https://ci.brave.com/job/brave-browser-build-pr/job/pr5290_handle_branded_wallpaper_noti_for_sr_1.8.x/2/execution/node/280/log/

Will check this out

[bsclifton]

Linux had an issue too:

14:08:29  ../../brave/browser/extensions/api/settings_private/brave_prefs_util.cc:22:7: error: use of undeclared identifier 'ntp_background_images'
14:08:29  using ntp_background_images::prefs::kNewTabPageSuperReferralThemesOption;
14:08:29        ^
14:08:29  ../../brave/browser/extensions/api/settings_private/brave_prefs_util.cc:24:5: error: use of undeclared identifier 'ntp_background_images'
14:08:29      ntp_background_images::prefs::kNewTabPageShowSponsoredImagesBackgroundImage;
14:08:29      ^
14:08:29  ../../brave/browser/extensions/api/settings_private/brave_prefs_util.cc:25:7: error: use of undeclared identifier 'ntp_background_images'
14:08:29  using ntp_background_images::prefs::kNewTabPageShowBackgroundImage;
14:08:29        ^
14:08:29  ../../brave/browser/extensions/api/settings_private/brave_prefs_util.cc:71:24: error: use of undeclared identifier 'kNewTabPageSuperReferralThemesOption'
14:08:29    (*s_brave_whitelist)[kNewTabPageSuperReferralThemesOption] =
14:08:29                         ^
14:08:29  ../../brave/browser/extensions/api/settings_private/brave_prefs_util.cc:74:24: error: use of undeclared identifier 'kNewTabPageShowSponsoredImagesBackgroundImage'
14:08:29    (*s_brave_whitelist)[kNewTabPageShowSponsoredImagesBackgroundImage] =
14:08:29                         ^
14:08:29  5 errors generated.

https://ci.brave.com/job/brave-browser-build-pr/job/pr5290_handle_branded_wallpaper_noti_for_sr_1.8.x/2/execution/node/360/log/

[bsclifton]

CI looks good! There was one browser test failure on macOS:

17:36:22  [507/507] BraveRewardsBrowserTest.NotVerifiedWallet (6341 ms)
17:36:22  1 test failed:
17:36:22      BraveRewardsBrowserTest.NotVerifiedWallet (../../brave/components/brave_rewards/browser/rewards_service_browsertest.cc:2323)

https://ci.brave.com/job/brave-browser-build-pr/job/pr5290_handle_branded_wallpaper_noti_for_sr_1.8.x/4/execution/node/681/log/

This is a known intermittent issue captured with brave/brave-browser#9339

Ready for uplift consideration 😄

[kjozwiak]

QA verified the PRs on Nightly as per #4866 (comment) and #5290 (comment)

[kjozwiak]

Uplift into 1.8.x approved after deliberating with @brave/uplift-approvers. Please make sure that all the correct labels are being used and the associated issue is moved into the correct milestone.