Vultr: Introducing vr_startup_script_facts module (#43004)

This commit introduces a new module called vr_startup_script_facts.

This module aims to return the list of startup scripts avaiable
avaiable in Vultr.

Sample available here:

```
"vultr_startup_script_facts": [
  {
    "date_created": "2018-07-19 08:52:55",
    "date_modified": "2018-07-19 08:52:55",
    "id": 327140,
    "name": "myteststartupscript",
    "script": "#!/bin/bash\necho Hello World > /root/hello",
    "type": "boot"
  }
]
```

test/legacy/roles/vr_startup_script_facts/defaults/main.yml

@@ -0,0 +1,3 @@
+startup_script_name: myteststartupscript
+startup_script_type: boot
+startup_script_content: "#!/bin/bash\necho Hello World > /root/hello"

test/legacy/roles/vr_startup_script_facts/tasks/main.yml

@@ -0,0 +1,30 @@
+# Copyright (c) 2018, Yanis Guenane <yanis+ansible@guenane.org>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+---
+- name: Create the script
+  vr_startup_script:
+    name: '{{ startup_script_name }}'
+    script_type: '{{ startup_script_type }}'
+    script: '{{ startup_script_content }}'
+
+- name: test gather vultr startup script facts in check mode
+  vr_startup_script_facts:
+  check_mode: yes
+
+- name: verify test gather vultr startup script facts in check mode
+  assert:
+    that:
+    - ansible_facts.vultr_startup_script_facts|selectattr('name','equalto','{{ startup_script_name }}') | list | count == 1
+
+- name: test gather vultr startup script facts
+  vr_startup_script_facts:
+
+- name: verify test gather vultr startup script facts
+  assert:
+    that:
+    - ansible_facts.vultr_startup_script_facts|selectattr('name','equalto','{{ startup_script_name }}') | list | count == 1
+
+- name: Delete the script
+  vr_startup_script:
+    name: '{{ startup_script_name }}'
+    state: absent

test/legacy/vultr.yml

@@ -19,5 +19,6 @@
     - { role: vr_ssh_key, tags: test_vr_ssh_key }
     - { role: vr_ssh_key_facts, tags: test_vr_ssh_key_facts }
     - { role: vr_startup_script, tags: test_vr_startup_script }
+    - { role: vr_startup_script_facts, tags: test_vr_startup_script_facts }
     - { role: vr_user, tags: test_vr_user }
     - { role: vr_user_facts, tags: test_vr_user_facts }