feat: job serialize and unserialize #1

.gitlab-ci.yml

devenv.nix

errors.go

import.go

job-handler.go

job.go

job_test.go

manager.go

manager_test.go

runnable-counter.go

runnable-dummy.go

runnable-fileoperation.go

runnable-gorm.go

runnable-http.go

runnable-mail.go

runnable-sftp.go

runnable-shell.go

state.go

state_test.go