Direct registration of files to database

[jennydaman]

We observed a performance bottleneck with the django backend of CUBE. FNNDSC/ChRIS_ultron_backEnd#546

This PR registers files to the database directly, instead of via CUBE's API. This is advantageous for several reasons:

• file registration can be done in bulk: specifically, two SQL commands to register 100 files
  • First SQL adds the AE title of PACS to the pacsfiles_pacs table, second SQL registers the files in bulk.
  • ChRIS_ultron_backEnd registers files one-by-one using ORM, which probably means 200-400 SQL commands for registering 100 files.
• Handling of duplicate rows in pacsfiles_pacs is achieved using native PostgreSQL features (INSERT INTO ... ON CONFLICT DO NOTHING)
• Using SQL transactions guarantees atomicity, making it safer to run multiple workers/replicas
• the whole process is now free of slow Python code!

Other changes:

• UUID replaced with ULID
• C-STORE supports promiscuous mode Storescp promiscuous mode Enet4/dicom-rs#477
• OpenTelemetry client uses gRPC instead of HTTP
• Environment variables renamed to start with OXIDICOM_ prefix

Not yet implemented: oxidicom custom metadata spec.