Merge the database dump scripts into db-dump

garmin-dump, weather-dump and library-dump differed only in project, database and rotation; one
db-dump PROJECT DATABASE week|day replaces them. The units keep their names and only change ExecStart.

.config/systemd/user/weather-dump.service

@@ -5,7 +5,7 @@ StartLimitBurst=4
 
 [Service]
 Type=oneshot
-ExecStart=%h/.local/bin/weather-dump
+ExecStart=%h/.local/bin/db-dump ens-forecast Weather week
 # MariaDB not up yet (e.g. caught up right after boot)? retry a few times
 Restart=on-failure
 RestartSec=5min