Client Certificate Authentication Support

[rhclayto]

Client Certificate Authentication Support

• Resolves: #

Summary

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

[rhclayto]

Code from #52198 .

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[icewind1991]

I don't think it's good to unconditionally send the client certificates for all requests.

The correct approach would probably be to allow configuring client certificates per domain.

The configuration being something like

$CONFIG = [
  'http_client_tls' = [
    'example.com' => [
      'cert' => '...',
      'key' => '...',
    ],
  ],
];