Improve the rule violations endpoint to take resolutions into account

[sschuberth]

Currently, https://eclipse-apoapsis.github.io/ort-server/api/get-rule-violations-by-run-id seems to always return all rule violations, independently whether they have already been resolved, e.g. via an .ort.yml rule violation resolution, or not.

The endpoint should be improved to return also at least a boolean to indicate whether a rule violation has been resolved, to that the could only show unresolved rule violations, or pre-configure a UI filter accordingly.

Maybe some additional information about a rule violation resolution would be nice, like the place where it's configured. So instead of a boolean, there could be a ResolutionType enum saying UNRESOLVED, RESOLVED_BY_REPO_CONFIG, etc.

[mnonnenmacher]

Maybe some additional information about a rule violation resolution would be nice

IMO it should include the whole resolution so that the rationale can be shown in the UI.