Move package request routes and related routes to their
respective routers. In addition, move some utility used
for requests over from `aurweb.packages`.
Introduced routers:
- `aurweb.routers.requests`
Introduced package:
- `aurweb.requests`
Introduced module:
- `aurweb.requests.util`
Changes:
- Moved `aurweb.packages.validate` to `aurweb.pkgbase.validate`
- Moved requests listing & request closure routes to
`aurweb.routers.requests`
- Moved pkgbase request creation route to `aurweb.routers.pkgbase`
- Moved `get_pkgreq_by_id` from `aurweb.packages.util` to
`aurweb.requests.util` and fixed its return type hint.
Signed-off-by: Kevin Morris <kevr@0cost.org>
