Uplift Unstoppable Domains & ENS native support to 1.22.x

[yrliou]

Uplift of #7702 #8125 #8135 #8214 #8212 #8131
Original Issues:

• Support Unstoppable Domains via DoH behind a feature flag Support Unstoppable Domains via DoH behind a feature flag brave-browser#14099
• Add ENS support Add ENS support brave-browser#14477
• Do not show opt-in page for decentralized DNS support in OTR contexts Do not show opt-in page for decentralized DNS support in OTR contexts brave-browser#14488
• Fix decentralized dns interstitial css Interstitial pages are missing (i) icon and have unreadable white text on light gray button brave-browser#14633
• Treat decentralized DNS servers as available before first probe is completed [Decentralized DNS] This site can't be reached error page is shown after opt-in to Unstoppable Domains or ENS from the interstitial page before the actual page is loaded brave-browser#14513
• Enable decentralized dns feature flag by default Enable decentralized DNS feature flag by default brave-browser#14517

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.

[yrliou]

pre-init failed with npm ERR! missing script: pylint-report
post-init failed with some unrelated audit-dep error
Otherwise CI looks good.

[kjozwiak]

pre-init failed with npm ERR! missing script: pylint-report
post-init failed with some unrelated audit-dep error
Otherwise CI looks good.

• npm ERR! missing script: pylint-report has been fixed via Pylint uplift. #8298
• audit-dep issue was fixed via Bump the rust generic-array dependency #8276

Both unrelated as @yrliou mentioned above 👍

[kjozwiak]

Uplift into 1.22.x approved after deliberating with @brave/uplift-approvers. QA has verified the PR on Nightly via the brave/brave-browser#14099 (comment), brave/brave-browser#14477 (comment), brave/brave-browser#14488 (comment), brave/brave-browser#14633 (comment), brave/brave-browser#14513 (comment).