feat(skore): Get `CrossValidationReport` by id

[thomass-dev]

Blocked by #1885, #1886 and https://github.com/probabl-ai/skore-hub/issues/555.

The goal of this issue is to be able to do in skore project.get("id") with id being the ID displayed by the CrossValidation page in skore-hub.

The ID must be unique in skore-hub for all types of reports, we don't want to have to add the report type in the get command.