Make the Data Layers finder keep Escape, its category and keyboard users

- Escape in the field closes the search alone, focus back on its button,
  without folding the panel or leaving the cockpit.
- The category is the group's key (LayerRows' data-group), so a language
  change keeps it; a group that goes away clears it.
- On and Off follow whether the layer is enabled, not its feed's state.
- The filter is a disclosure of two groups of toggle buttons: opening it
  focuses the chosen option, the arrows, Home and End move, Escape closes
  it, and it stays inside the panel.
- No layers match is translated, the search matches names only, and the
  rows are filtered once per frame at most.
- A voice request to show a layer the finder hides clears the finder.

Co-authored-by: Manjunath Paparaju <[email protected]>

src/i18n/locales/de.json

@@ -3638,5 +3638,6 @@
   "Status": "Status",
   "Search layers…": "Ebenen suchen…",
   "Layer groups": "Ebenengruppen",
-  "Jump to {name}": "Zu {name} springen"
+  "Jump to {name}": "Zu {name} springen",
+  "No layers match": "Keine passenden Ebenen"
 }