Full Pytest and unittest compatibility

[Liam-DeVoe]

HypoFuzz is compatible with almost all of Pytest and unittest (and all of the most-commonly used parts of both). This issue tracks the remaining work to get 100% compatibility, as mentioned on the compatibility docs page.

• Pytest's xunit-style setup and teardown methods
  • setup_module and teardown_module
  • setup_class and teardown_class
  • setup_method and teardown_method
  • setup_function and teardown_function
• Unittest features not supported by Pytest
  • subTest
  • the load_tests protocol

Note to self: if adding support for any of these, also update the wording on https://hypofuzz.com/docs/compatibility.html.