Implement GitLab integration setup

[atomic111]

need to be designed similar to GitHub

variable "gitlab_token" {
  description = "The GitLab Token"
  type        = string
  sensitive   = true
}

resource "mondoo_integration_gitlab" "gitlab_integration" {
  name  = "GitLab Integration"
  
  base_url = "" # optional, otherwise gitlab.com 
  group = "" # optional, otherwise all groups are discovered

	# configure discovery options  
  discovery {
		groups = true
		projects = true
		terraform = true
		k8s_manifests = true
  }

  credentials = {
    token = var.gitlab_token
  }
}

[mati007thm]

@atomic111 The PR is ready: #167