We probably want to have a stand-alone repo for the testing suite

There's some issues with the current setup:

• The initial lockfile is using a currently invalid cashscript version
• Missing url-join dependency
• uses ts-node-esm in some places instead of tsx
• The compilation fails with the latest node versions (needed to add cross-env)
• The testing-suite is also missing a README.md and a .gitignore
• Seems to crash on failing tests