feat: mysql-bkup v2 on bkupkit

MysQL backup and restore built on the shared bkupkit core:
streaming end to end, with no dump held in memory or written to
local disk.

examples/docker-compose.scheduled.local.yaml

@@ -1,4 +1,3 @@
-version: "3"
 services:
   mysql-bkup:
     # In production, it is advised to lock your image tag to a proper
@@ -11,7 +10,7 @@ services:
     environment:
       - DB_PORT=3306
       - DB_HOST=mysql
-      - DB_USERNAME=userName
+      - DB_USER=userName
       - DB_PASSWORD=${DB_PASSWORD}
       # See: https://jkaninda.github.io/mysql-bkup/reference/#predefined-schedules
       - BACKUP_CRON_EXPRESSION=@daily #@every 5m|@weekly | @monthly |0 1 * * *