feat(init-1D): #MA-1066 add init schoolyear period

[flmartineau]

Describe your changes

• add initilization of the school year period from the init form data

Checklist tests

• check that period creation/update is still working properly in vie-scolaire settings
• check that the school year dates have been properly modified/created from the init data

Issue ticket number and link

https://jira.support-ent.fr/browse/MA-1066

Checklist before requesting a review (magic string, indentation, comment/documentation...)

• [x] I have detailed the tests to do in my feature/fix in order to prevent consequents regressions (must specify in Checklist tests)
• [x] I have performed a self-review of my code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation (API Doc etc...) - (must specify in Description for target version)
• [ ] If it is a consequent feature, I have added thorough tests.
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] Any dependent changes have been added to this project (must specify in Description)