chore: github workflow to run tests

[thlorenz]

Adding github workflow to run rust tests as well as integration tests. As part of that cleaned up use of nightly feature and removed dependency on cargo-expand module in order to keep the workflow fast.

• chore: build+test workflow
• chore: remove str_split feature annotation
• chore: setup dart and pub for ci tests
• chore: adding llvm to github actions
• rid-build: expanding without cargo expand
• chore: rustc expand needs nightly rust
• chore: final cleanup of github action