Add support for dynamic, express and expirable P3A metrics, add NTP SI/creative metrics

[DJAndries]

Resolves brave/brave-browser#24318, brave/brave-browser#24319 and brave/brave-browser#24609.

Submitter Checklist:

• [ ] I confirm that no security/privacy review is needed, or that I have requested one
• [ ] There is a ticket for my issue
• [ ] Used Github auto-closing keywords in the PR description above
• [ ] Wrote a good PR/commit description
• [ ] Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• [ ] 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)

Reviewer Checklist:

• [ ] A security review is not needed, or a link to one is included in the PR description
• [ ] 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:

0. Start with fresh profile, ensure ads is disabled, ensure no metrics with the prefix creativeInstanceId exist in the local state page.
1. Open new tabs until an ad is shown. Verify one creative metric with the suffix views exists in the local state page.
2. Click on the creative, verify one creative metric with the suffix clicks exists in the local state page.
3. Verify that the metrics are sent (by using a mitm proxy), with the header X-Brave-P3A-Creative set to true.
4. Close browser, advance the time by one day, open browser, ensure the metrics are resent.
5. Close browser, advance the time by seven days, open browser, ensure metrics are not sent (due to expiry).