Move rsnapshot functionality to supplemental/rsnapshot

Both postgres and mysql require the rsnapshot role to run first!
1 job for master in 27 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #4962
test

00:00:27

 
Name Stage Failure
failed
test Test
yamllint 1.15.0
$ yamllint .
./mysql/defaults/main.yml
7:81 warning line too long (118 > 80 characters) (line-length)

./mysql/tasks/main.yml
73:1 error trailing spaces (trailing-spaces)

ERROR: Job failed: exit code 1