admin: tab system improvement, search: ?search qp

tab content classes (e.g. settingsList, activityList)
can implement "AsTab", "Navigatable" and or "PageEventBindable",
the first giving them a tab name, a subpath and a reloader function,
the second an "isURL" and "navigate" function for loading resources,
the last giving them bind/unbindPageEvent methods. These are looped
through in ts/admin.ts still crudely, maybe tabs.ts could accept "AsTab"
implementers directly.

"Search" class now has a ?search query param which just encodes the
search box content, set when you perform a server search (hit enter or
press the button). ?user queries from the accounts or activity tab will
be converted to this form on loading.

ts/modules/invites.ts

@@ -784,6 +784,8 @@ class DOMInvite implements Invite {
 }
 
 export class DOMInviteList implements InviteList {
+    readonly tabName = "invites";
+    readonly pagePath = "";
     private _list: HTMLDivElement;
     private _empty: boolean;
     // since invite reload sends profiles, this event it broadcast so the createInvite object can load them.
@@ -804,14 +806,14 @@ export class DOMInviteList implements InviteList {
             this.focusInvite(event.detail);
         });
 
-    isInviteURL = () => {
-        const urlParams = new URLSearchParams(window.location.search);
+    isURL = (url?: string) => {
+        const urlParams = new URLSearchParams(url || window.location.search);
         const inviteCode = urlParams.get("invite");
         return Boolean(inviteCode);
     };
 
-    loadInviteURL = () => {
-        const urlParams = new URLSearchParams(window.location.search);
+    navigate = (url?: string) => {
+        const urlParams = new URLSearchParams(url || window.location.search);
         const inviteCode = urlParams.get("invite");
         this.focusInvite(inviteCode, window.lang.notif("errorInviteNotFound"));
     };