Zabbix settings backup, Readme update, base calls location move

New module for zabbix settings backup based on zabbix-dump

Move the _BORG_CALL and _BORG_PRUNE base calls to functions.check
instead of each module (they are all the same)

Update Readme file

Update default settings and remove KEEP so the original defaults are
used

borg.backup.zabbix.settings-default

@@ -0,0 +1,17 @@
+# Borg backup wrapper scripts settings: gitea
+
+# rename to borg.backup.gitea.settings to use
+
+# override settings in borg.backup.settings with SUB_ prefix
+# valid for BACKUP_FILE, BACKUP_SET, COMPRESSION*, KEEP_*
+
+# location for the zabbix dump script
+# Source: https://github.com/npotorino/zabbix-backup
+# if not set use /usr/local/bin
+ZABBIX_DUMP="";
+# either psql or mysql, must be set
+ZABBIX_DATABASE="";
+# config location (default /etc/zabbiz/zabbix_server.conf)
+ZABBIX_CONFIG="";
+# unknown tables, default ignore, is set to true, will force backup them
+ZABBIX_UNKNOWN_TABLES="";