feat(FastAPI): add /pkgbase/{name}/delete (get, post)

In addition, we've had to add cascade arguments to backref so
sqlalchemy treats the relationships as proper cascades.

Furthermore, our pkgbase actions template was not rendering
actions properly based on TU credentials.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/routers/packages.py

@@ -940,3 +940,40 @@ async def pkgbase_disown_post(request: Request, name: str,
     disown_pkgbase(pkgbase, request.user)
     return RedirectResponse(f"/pkgbase/{name}",
                             status_code=int(HTTPStatus.SEE_OTHER))
+
+
+@router.get("/pkgbase/{name}/delete")
+@auth_required(True)
+async def pkgbase_delete_get(request: Request, name: str):
+    if not request.user.has_credential("CRED_PKGBASE_DELETE"):
+        return RedirectResponse(f"/pkgbase/{name}",
+                                status_code=int(HTTPStatus.SEE_OTHER))
+
+    context = make_context(request, "Package Deletion")
+    context["pkgbase"] = get_pkg_or_base(name, PackageBase)
+    return render_template(request, "packages/delete.html", context)
+
+
+@router.post("/pkgbase/{name}/delete")
+@auth_required(True)
+async def pkgbase_delete_post(request: Request, name: str,
+                              confirm: bool = Form(default=False)):
+    pkgbase = get_pkg_or_base(name, PackageBase)
+
+    if not request.user.has_credential("CRED_PKGBASE_DELETE"):
+        return RedirectResponse(f"/pkgbase/{name}",
+                                status_code=int(HTTPStatus.SEE_OTHER))
+
+    if not confirm:
+        context = make_context(request, "Package Deletion")
+        context["pkgbase"] = pkgbase
+        context["errors"] = [("The selected packages have not been deleted, "
+                              "check the confirmation checkbox.")]
+        return render_template(request, "packages/delete.html", context,
+                               status_code=int(HTTPStatus.EXPECTATION_FAILED))
+
+    packages = pkgbase.packages.all()
+    for package in packages:
+        delete_package(request.user, package)
+
+    return RedirectResponse("/packages", status_code=int(HTTPStatus.SEE_OTHER))