New backend functionnality : GetAnalysis

[Antoine-Germon]

Describe your changes

added getAnalysis method, it returns the user's top genres based on his favourite artists resolves #5

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] I have read the PULL_REQUEST_TEMPLATE as well as the CODE_OF_CONDUCT
• [ ] If it is a core feature, I have added thorough tests.