feat: Bill anniversary subscriptions

[vincent-pochet]

Context

We want to add the ability to choose to bill users at subscription date anniversary and not only on a calendar basis.

Changes

The objective of this pull request is to take anniversary subscriptions into account in the BillingService

It will:

• Bill weekly subscriptions on their weekly anniversary day
• Bill monthly subscriptions on their monthly anniversary day, taking into account month duration for subscription day > 28
• Bill yearly subscriptions on their yearly anniversary day, taking into account year duration for subscription = February 29th when year is not a leap year
• Bill fees for yearly subscriptions with monthly fee billing on their monthly anniversary taking into account month duration for subscription day > 28

Related resources

This PR follows:

• feat: Update Subscription data model to support anniversary date #352 to update the subscription data model.
• feat: Add new date service to compute bounds for subscription and charge fees #360 to add a new date service for invoice bounds
• feat: Expose billing time into GraphQL queries and mutations #364 to expose billing time into GraphQL
• feat: Expose billing time into API endpoint #365 to expose billing time into API