search: fix server-side dates, add mentionedUsers, referrer, time

QueryDTO.Value being classed as "any" meant DateAttempts would be
unmarshaled as map[string]any, so a custom UnmarshalJSON checks the data
type and unmarshals into a DateAttempt if needed. mentionedUers,
referrer and time matching implemented for activity search. Also, fixed
multi-class queries (e.g. date -and- bool for last-active).

ts/modules/search.ts

@@ -373,7 +373,8 @@ export class Search {
                         this._c.search.oninput((null as Event));
                     };
                 }
-            } else if (queryFormat.string) {
+            }
+            if (queryFormat.string) {
                 q = new StringQuery(queryFormat, split[1]);
 
                 q.onclick = () => {
@@ -383,7 +384,8 @@ export class Search {
                     }
                     this._c.search.oninput((null as Event));
                 }
-            } else if (queryFormat.date) {
+            }
+            if (queryFormat.date) {
                 let [parsedDate, op, isDate] = DateQuery.paramsFromString(split[1]);
                 if (!isDate) continue;
                 q = new DateQuery(queryFormat, op, parsedDate);