Copy a feature's error or warning message from the history menu (#1226)

The feature menu in the timeline and Feature History gets a Copy Message item for a feature's error or warning, translated, with a test.

assets/locales/de.json

@@ -687,6 +687,8 @@
   "Drive Joint": "Gelenk antreiben",
   "Edit Profile Sketch": "Profile-Skizze bearbeiten",
   "Find in Browser": "Im Browser suchen",
+  "Copy Error Message": "Fehlermeldung kopieren",
+  "Copy Warning Message": "Warnmeldung kopieren",
   "Report a bug — review a screenshot and open a GitHub draft": "Fehler melden — Screenshot prüfen und einen GitHub-Entwurf öffnen",
   "Reset Toolbar": "Symbolleiste zurücksetzen",
   "Select bodies (a face picks its body)": "Körper auswählen (eine Fläche wählt ihren Körper)",