(these variables are independent from each other, but I'm putting them both in the same task as it's probably less work to handle them both at once)
It should be set the same way we currently have SWH_SENTRY_DSN.
`SWH_MAIN_PACKAGE` names must be dotted package names (`swh.indexer`, `swh.storage`, etc.)
Choosing `SWH_SENTRY_ENVIRONMENT` names are left to the implementer of this task, but I suggest `production` and `staging`, as they match both our terminology and Sentry's.
https://docs.sentry.io/workflow/releases/?platform=python
https://docs.sentry.io/enriching-error-data/environments/?platform=python