An issue in SOFA, is that the mappings (apply, applyJ, applyJT etc) are applied through visitors, which depends on the scene graph. It's up to the user to define the scene graph, and there is a lot of possibilities. In some cases, the user defines a scene graph that does not correspond to the mapping graph, a DAG linking mappings and their input and output.

This PR replaces the mapping visitors by a simple function dedicated to the traversal of the mapping graph.

This solution avoids to refactor the visitor mechanism. Only a sub-part of the mechanical operations is affected.

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Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).