Use the CommonConfiguration structure for roles.

[razvan]

Description

Part of #273

Refactor the SparkApplication CRD to be more in line with other operators.

The three main roles (job, driver and executor) are now concrete RoleGroup objects under an Role named "default" that is constructed by the operator internally.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author
- [x] Changes are OpenShift compatible
- [ ] CRD changes approved
- [x] Helm chart can be installed and deployed operator works
- [x] Integration tests passed (for non trivial changes)

# Reviewer
- [x] Code contains useful comments
- [x] Documentation added or updated
- [x] Changelog updated
- [x] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[razvan]

:green_circle: CI https://ci.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/spark-k8s-operator-it-custom/101/

[razvan]

:green_circle: CI: https://ci.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/spark-k8s-operator-it-custom/103/