Add volume creation without attachment

resource.digitalocean_volume.this.tf

@@ -0,0 +1,8 @@
+resource "digitalocean_volume" "this" {
+  count                   = var.volume_size == 0 ? 1 : 0
+  description             = "Data Volume for ${var.host_name}.${var.domain_name}"
+  initial_filesystem_type = "ext4"
+  name                    = "${var.host_name}.${var.domain_name}"
+  region                  = var.region
+  size                    = var.volume_size
+}

variable.volume_size.tf

@@ -0,0 +1,4 @@
+variable "volume_size" {
+  default = "0"
+  type    = number
+}