Refactoring service/db layers

some notes by @opqdonut @Macroz about possible ideas

- [ ] decide about plurals. Now we have `rems.db.form` but `rems.db.licenses` and `rems.services.attachment` but `rems.db.attachments`
- [x] create missing `rems.services.form` (#2180)
- [ ] unify ids, now we have for example `:id`, `:licid` and `:license/id`. Return `:license/id` already from the db.
- [ ] unify ids, now we have for example `:wfid`, `:catid` etc. Prefer `:workflow/id` and `:catalogue-item/id` or something.
- [ ] decide where to join the related entities i.e. the responsibilities between the levels should be clear (i.e. where do you join/enrich the license of resource and organization of license?), who formats for internal and who for API?
- [ ] db.applications uses all the other db namespaces and probably the functionality is at the wrong level
- [ ] decide where to cache stuff and do it one way for everything
- [ ] document decisions in architecture docs / ADR
- TODO more