Add component attribute to stack configs. Allow configuring and provisioning many instances of the same component.

[aknysh]

what

• Add component attribute to stack configs

why

• Allow specifying YAML configs and provisioning many instances of the same component type.
  For example, we can specify the following config to provision many different instances of AWS Aurora clusters by referencing the common aurora-postgres component:

components:
  terraform:
    db1:
      component: aurora-postgres
      vars:
        instance_type: db.r4.large
        cluster_size: 1
    db2:
      component: aurora-postgres
      vars:
        instance_type: db.r4.large
        cluster_size: 1
    db3:
      component: aurora-postgres
      vars:
        instance_type: db.r1.large
        cluster_size: 1
    db4:
      component: aurora-postgres
      vars:
        instance_type: db.r8.large
        cluster_size: 1

and then use the following commands to plan/apply the database components:

atmos terraform plan db1 -s uw2-prod
atmos terraform apply db1 -s uw2-prod

atmos terraform plan db2 -s uw2-prod
atmos terraform apply db2 -s uw2-prod

atmos terraform plan db3 -s uw2-prod
atmos terraform apply db3 -s uw2-prod