swarm-ui: choose the review classifier's runtime on the settings page

The classifier settings page showed model and effort only, so the API-key
or ACP runtime could be switched only through a raw API call. It now has a
runtime select, and under ACP the provider's URL, model and prices. A PUT
carries the provider only on the ACP runtime, so the stored record stays
for a switch back. Closes #5249

frontend/packages/swarm-ui/src/pages/review-settings/ClassifierSettings.css

@@ -1,4 +1,5 @@
-/* The settings form: the three fields on one line, then the save action. */
+/* The settings form: the fields wrap in a row, the provider fields on a row of
+ * their own under the ACP runtime, then the save action. */
 .ui-classifier-settings {
   display: flex;
   flex-direction: column;