Restructure into package and add tests

[brosaplanella]

The aim of this PR is to wrap the code into a package structure and add infrastructure.

• [x] Convert into package structure
• [x] Add test folders
• [x] Add Github workflows
• [x] Setup Codecov
• [x] Add example folders
• [x] Setup docs
• [x] Update README (very basic)

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (main@ced0b46). Click here to learn what that means. Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4 +/- ## ====================================== Coverage ? 9.02% ====================================== Files ? 7 Lines ? 432 Branches ? 0 ====================================== Hits ? 39 Misses ? 393 Partials ? 0 ```

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