Add stepper to help user

[annelhote]

https://dataesr.github.io/react-dsfr/?path=/docs/composants-indicateur-d-%C3%A9tapes-stepper--first-step

[annelhote]

As we have a lots of interactions at different moment, it could be useful to have a step-by-step process to help the user in the decision. Plus a guided tour for the first usage could be useful. Here are the steps:

1. Querying data :
   • Do I want to start a new session ?
   • Do I want to restore a previous session ?
   • Do I want to import a list of publications (TBD, see Import a list of publications #23) ?
2. Deciding affiliations
   • Do I want to restore previously decided affiliations ?
   • Do I want to start from scratch ?
3. Ending session
   • Do I want to export my ongoing session in order to be able to restore it later ?
   • Do I want to export the decided affiliations to be able to restore it later ?
   • Do I want to export the works in the BSO format ?