Re-write CI using the new maintainer tools script. A few things to note:
- Put sanitizer and wasm jobs in their own scripts
- Utilize `extra_tests.sh` for additional feature combos
- We are exceeding the 20 job limit, see the README
Unless I'm made a mistake this shouldn't reduce the test coverage in any
way.
The `just` command makes scripts and commands discoverable for new devs
and old devs alike when switching between repos.
Add a justfile copied from bitcoin with changes as required.
Tobin C. Harding