feat(nav): tabs, list views and name searches are named in the address

Settings, Configuration and Users name their tab (stab/cfgtab/utab); a link's tab wins and a tab pre-selected
while its page is on screen now switches it. A playlist's sort, filters and grouping (plsort/plf/plgroup), the
Files sort (fsort, always written) and the name searches of Channels, Files, Playlists and Plex (cq/fq/plq/pq+pqf)
reopen from the address; the searches are written once the typing pauses.

frontend/src/lib/configTab.ts

@@ -0,0 +1,3 @@
+// The Configuration page's address-bar key: the config group its tab rail shows. Here, beside the other
+// pages' keys, so the page's definition can declare it without importing the lazy page.
+export const CONFIG_TAB_KEY = "cfgtab";