Initial data logging implementation.

Similar approach to radio.

Add tests with vitest. At some point we'll try to switch to vite to
build this so pick an aligned test runner.

Author: microbit-matt-hillsdon

ci-build.sh

@@ -12,4 +12,4 @@ git clone https://github.com/emscripten-core/emsdk.git ~/.emsdk
 ~/.emsdk/emsdk activate latest
 source ~/.emsdk/emsdk_env.sh
 
-npm run build
+npm run test && npm run build