87559cc8

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Drop backward compat; add sydtest-mutation-example-gen for multi-suite e2e test

- Remove legacy JSON array decoding for covering_tests; it is now always a
  JSON object keyed by suite name
- mutation-checks.nix now uses testSuites everywhere
- Add sydtest-mutation-example-gen package with a property-test suite that
  tests addOne from a different angle, demonstrating multi-suite mutation testing
- mutation-checks.nix wires both example suites together and expands
  safe-coloured-text to include layout and parsing packages

Timeline