fix(privacy): Improve cosmetic filtering performance on iOS

[StephenHeaps]

• Update setRulesOnStylesheetThrottled to throttle instead of debounce.
  • Currently we wait for a page to not have any mutations for 200ms before we update the stylesheet. This can result in us knowing about selectors to hide but not hiding them until a page has stopped mutating. By throttling instead, we update the stylesheet at most every 200ms.
• Cache previously hidden selectors for each eTLD+1 on the tab.
  • When we first inject SelectorsPollerScript.js we provide the page with a initial list of selectors to hide, then we send the remaining selectors on the page to CosmeticFiltersScriptHandler to check against AdblockEngine. The AdblockEngine tells us which selectors to hide, and we send these back to the page to be hidden.
  • By caching these selectors (in memory only, cached per-tab), we can then inject them with the initial when we first inject SelectorsPollerScript.js so we don't have to wait for the round trip from our javascript -> ScriptHandler -> AdblockEngine -> our javascript. This cache is reset when:
    • Tab is closed / browser restart.
    • Tab eTLD+1 is changed.
    • Filter lists are updated.
    • Global shields level (standard/aggressive) is changed.
    • Domain specific shields level is changed.

Resolves brave/brave-browser#42530

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• 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 wiki
  • npm run presubmit wiki, 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/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[github-actions]

Chromium major version is behind target branch (132.0.6834.111 vs 133.0.6943.27). Please rebase.