Fixes #24097: Skipped directive does not show in node compliance tree

[clarktsiory]

https://issues.rudder.io/issues/24097

Essentially the same as #5600, and with some refactoring :

• move the Elm model for SkippedDirective to the Elm Compliance.Datatypes module
• compute the skipped directives in a method which takes the conversion DirectiveComplianceOverride => T as a param, either ByRuleDirectiveCompliance or ByRuleDirectiveCompliance (this PR)

[fanf]

So, the code looks good and we now have skipped in node, but I still think there is something broken: in the case where the rule has only one directive and that directive is skipped, then the rule doesn't appear at all in the node.

Step to reproduce: in your screenshot example, remove the directive "File download (HTTP)" from rule "Install package skip"

[fanf]

I'm going to merge that one as it is, it's already a nice enhancement, and then I'm opening a new issue for the remaining problem for rule with all directive skipped.

[Normation-Quality-Assistant]

This PR is not mergeable to upper versions.
Since it is "Ready for merge" you must merge it by yourself using the following command:
rudder-dev merge https://github.com/Normation/rudder/pull/5630
-- Your faithful QA
Kant merge: "Science is organized knowledge. Wisdom is organized life."
(https://ci.normation.com/jenkins/job/merge-accepted-pr/84211/console)

[clarktsiory]

OK, merging this PR

[clarktsiory]

OK, merging this PR