Attach extra volumes for stateful services

Attach extra data disks to the nodes that require data persistence and data safety, such as postgres.

Changes:
Terraform

1. Add data_disk_type and data_disk_size in tencentcloud module to configure data disks. If data_disk_size is null, no disk will be created.
2. Add <service>_data_disk_size on dedicated services in the gitlab_ref_arch_tencentcloud. Currently only elastic, gitaly, postgres and redis have the options based on our requirements.

Ansible

1. In ansible common role, add variable data_disk to determine whether mount the disk or not. If the data_disk is found, the disk will be mounted to /var/opt/gitlab when it is an omnibus node or /var/lib/docker when it is a elasticserch node.