[WIP] linode_instance resource matches API

[displague]

Refactors instances, configs, and disks to align more with the Linode API.

Covers several recommendations from #16 and additional feedback.

Adds support for Stackscripts: Closes #9

Refactor Todo (each requiring passing tests)

• [ ] Instances
  • [x] Create
    • [x] With Disks
    • [x] With Configs
    • [x] Mixed Disks and Configs
    • [x] Mixed Disks and Configs and Volumes
  • [x] Read
    • [x] With Disks
    • [x] With Configs
    • [x] Mixed Disks and Configs
    • [x] Mixed Disks and Configs and Volumes
  • [ ] Update
    • [x] Simple (no disk or config changes. no-reboot or rebuild required)
    • [x] Resize Instance (requires reboot)
    • [ ] With Disks
    • [x] Simple (no reboot required)
    • [ ] Resize (reboot required)
    • [x] Add (no reboot required)
    • [ ] Delete (reboot required)
    • [ ] With Config
    • [ ] Simple (no-reboot or rebuild required)
    • [ ] Change Helper, Kernel, memory, virtualization, etc (reboot required)
    • [ ] Mixed Disks and Configs
    • [x] Add Disks to Config Device slots (reboot required)
    • [ ] Remove Disks from Config Device slots (reboot required)
    • [ ] Reorder Disks slots (reboot required)
    • [ ] Mixed Disks and Configs and Volumes
    • [ ] If volume change is for the booted config, try live attachments
      • [ ] Change Volumes slots (live mount capable)
      • [ ] Slot order changes for volumes, but disks (live mount capable)
    • [ ] handle disk order changes that require reboot
    • [x] ~Handle changes from simple image= format to config{} disk{} format (and vice-versa)~ force a rebuild? (yes)
  • [x] Delete
• [ ] describe these changes
  • [x] examples
  • [ ] resource docs

Example Resource

resource "linode_stackscript" "helloworld" {
  label = "hello world"
  script = <<EOF
#!/bin/bash
# <UDF name="gh_username" Label="GitHub Username" example="..." />
echo Hello, $GH_USERNAME
EOF
  images = ["linode/ubuntu18.04"]
  description = "the hello world of stackscripts"
  rev_note = "initial version"
}

resource "linode_instance" "simple" {
  label = "simple"
  type = "g6-nanode-1"
  region = "us-east"
  image = "linode/ubuntu18.04"
  swap_size = "256"
}

resource "linode_instance" "foo" {
  label = "advanced"
  type = "g6-nanode-1"
  region = "us-east"

  disk {
    label = "root"
    filesystem = "ext4"
    image = "linode/ubuntu18.04"
    size = "20000"
    root_pass = "b4d_p4s$"
    stackscript_id = "${linode_stacsckript.helloworld.id}"
    stackscript_data = {
      gh_username = "displague"
    }
  }

  disk {
    label = "forensics"
    filesystem = "ext4"
    image = "private/forensics"
    size = "2000"
    root_pass = "w04h_n311y"
  }

  disk {
     label = "swap"
     filesystem = "swap"
     size = "512"
  }

  config {
     label = "boot"
     kernel = "linode/latest-64bit"

     devices {
       sda = { disk_label = "root" }
       sdb = { disk_label = "swap" }
       sdc = { volume_id = "${linode_volume.foo.id}" }
     }
  }

  config {
     label = "forensics"
     kernel = "linode/latest-64bit"
     helpers {
       network = false
     }

     devices {
       sda = { disk_label = "forensics" }
       sdb = { disk_label = "boot" }
     }
  }

  boot_config = "boot"
}