Refactor CI and scripts

Huge overhaul to CI and scripts

The project is now managed with the command runner just.

All the commands that runs in CI (and more) are now easily accessible locally, e.g. generate coverage and view the coverage report with just test-coverage coverage-report (runs the test-coverage recipe and then the coverage-report` recipe).

Same for other complicated and elaborate workflows such as address sanitizing and benchmarks.

The CI is further refactored to reduce duplicate code.