Incorporate review suggestions

* Use Python 3.10.
* Add stages to pipeline.
* Introduce new file to be included locally and move default keyword
and extensions into that new file.
* Add stage keyword to all CI jobs.
* Reorder keywords in CI jobs that use extends keyword.
* Use full relative path to executable when calling app.
* Use needs keyword to define dependencies.
* Use artifacts sub-key of nedds keyword in favour of dependencies
keyword.