Generate additional test cases based on actual browser reports

[rspeed]

To improve real-world coverage, every known report should have its own test case.

• Make a list of every type of HPKP and CSP error.
• Create a website that is able to make browsers generate reports.
  • Ability to set (and possibly configure) both HPKP and CSP headers.
  • Ability to violate those settings.
• Create a second website for capturing reports.
  • Report API endpoint that doesn't really do anything.
  • Configure mitmproxy to sit in front of the report site, or integrate through its API.
• Run through each known error type using each of the major browsers.
• Export the raw requests and use them to create new test cases.

This will be an unrelated and rarely used codebase, so it'll go in an empty branch.