[RTR] Refactoring solver interface utils for the better

[Ipuch]

All Submissions:

• Have you followed the guidelines in our Contributing document [docs/contribution.md]?
• Have you checked to ensure there aren't other open [Pull Requests] for the same update/change?
• Have you opened/linked the issue related to your pull request?
• Have you used the tag [WIP] for on-going changes, and removed it when the pull request was ready?
• When ready to merge, have you sent a comment pinging @pariterre in it?

New Feature Submissions:

1. Does your submission pass the tests (if not please explain why this is intended)?
2. Did you write a proper documentation (docstrings and ReadMe)
3. Have you linted your code locally prior to submission (using the command: black . -l120 --exclude "external/*")?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new examples for your core changes, as applicable?
• Have you written new tests for your core changes, as applicable?

---

This change is 

[Ipuch]

Tests doesn't pass because of biorbd 1.10.1

[pariterre]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Ipuch)