add a sqlite backup option

[evanrich]

First of all, great app! It would be nice to have a backup option, similar to sonarr/radarr, where it backs up the sqlite database, either by copying it or by exporting a file, by running something like:

sqlite3 some.db .schema > schema.sql
sqlite3 some.db .dump > dump.sql

this would allow for recovery of large rulesets/tables/etc in case of corruption or other issues. I'm running this in kubernetes but should not matter, users could mount a seperate backup volume to the container to store the backups somewhere. Radarr/sonarr run backups on a schedule.

thanks!