change(python): move request & pkgbase request routes

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>

aurweb/requests/util.py

@@ -0,0 +1,13 @@
+from http import HTTPStatus
+
+from fastapi import HTTPException
+
+from aurweb import db
+from aurweb.models import PackageRequest
+
+
+def get_pkgreq_by_id(id: int) -> PackageRequest:
+    pkgreq = db.query(PackageRequest).filter(PackageRequest.ID == id).first()
+    if not pkgreq:
+        raise HTTPException(status_code=HTTPStatus.NOT_FOUND)
+    return db.refresh(pkgreq)