feat: xcresult reader (WIP)

[delatrie]

The PR adds support for xcresult files to Allure 3.

This is still WIP. Remaining work:

• Tidy up the tests, disable for non-MacOS
• Cover activities -> steps/attachments with more tests
• Cover different combinations of args/retries/devices with tests
• Check well-known activities -> Allure entities conversion
• Error traces
• Legacy API to bypass the new xcresulttool API bugs/limitations
  • Bug URLs
  • Better stack traces & source references
• Get rid of extra attachment-only steps

Improvements compared to allure-xcresults:

• Parametrized tests
• Destinations (a.k.a., devices)
• Attachments are chronological
• Suites
• Packages (bundles, which were suites previously)
• Tags
• Bugs

In this PR I experiment a little with sort of typed unknowns to move parsing checks from tests (which are tricky to write in case of ill-formed xcresult files) to the type system. I'm still in the process of figuring out if it is good enough to stay in the code base.