refactor SCC Registration flow

[rjpmestre]

What does this PR change?

This pr refactors SCC system register applying a chain of responsibility pattern.
As this flow does not have a dedicated documentation, having the steps decoupling increases readability and testability.

GUI diff

No difference.

• DONE

Documentation

• No documentation needed: only internal and user invisible changes

• DONE

Test coverage

• Unit tests were added

• DONE

Links

Fixes #

• DONE

Changelogs

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[github-actions]

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[github-actions]

Suggested tests to cover this Pull Request

[rjmateus]

LGTM but please wait for Kevin and MC review

[mcalmer]

some small nitpicks and checkstyle is failing. I think javadoc is missing.

[mcalmer]

We have 2023 :-)

[mcalmer]

Looks good to me. Check what you want to do about the SonarCloud error.