ARA V2 - Feature: Migrate tags

**Epic**
Migrate data (#507)

**Description**
Migrate tags.

Concept such as `branch`, `cycle`, `country`, `type`, `source` are replaced by tags. This has the following benefits:
- it is no longer required to have at least one of those concepts (e.g. some project does neither need cycles nor countries)
- fully customizable: there is no limit on tags association
- tags can be shared among concepts (e.g. same tag between scenario or feature)
- easier search
- performance enhancement: data is easily accessible (no more levels)