Refactor reported variant creators (for clinical interpretations)

[jtarraga]

Currently, clinical interpretations rely on three reported variant creators according to the interpretation analysis (Tiering, TEAM or default). They are responsible of creating the reported events (per disease panel and transcript) for each variant. Basically, a reported event consists of a panel disease, a list of sequence ontology terms (consequence types), the role in cancer, the ACMG classification, the clinical significance and a tier. Only assigning the tier is analysis dependent, so we should merge that reported variant creators in one creator, and delegate the tier assignation to the interpretation analysis itself.