Database update refactory and "intervals_count_by_build" endpoint

[3.2]

Added

• /intervals/intervals_count_by_build endpoint, which retuns the number of genes, transcripts, exons for each genome build

Changed

• Updated schug library to v1.10
• Disable SQLAlchemy logger
• To avoid timeout errors, update genes, transcripts exons only from pre-downloaded files from schug
• Documentation on how to update genes, transcripts and exons database tables
• Renamed Pydantic orm_mode config param to model_config

Removed

• Code for downloading resources from Ensembl using the schug library