feat: add created field to server and server_info modules (#381)

##### SUMMARY
Add missing "created" field to ansible result

based on documentation
https://docs.hetzner.cloud/#servers-get-all-servers

```
created
string required
Point in time when the Resource was created (in ISO-8601 format)
```

##### ISSUE TYPE
- Feature Pull Request

##### COMPONENT NAME
hcloud_server_info
hcloud_server

Co-authored-by: Pawel Urbanek <pawel.urbanek@medvc.eu>

changelogs/fragments/add_created_to_server_info.yaml

@@ -0,0 +1,3 @@
+minor_changes:
+  - hcloud_server_info - Add `created` field
+  - hcloud_server - Add `created` field

plugins/modules/hcloud_server.py

@@ -252,6 +252,11 @@ hcloud_server:
             returned: always
             type: str
             sample: my-server
+        created:
+            description: Point in time when the Server was created (in ISO-8601 format)
+            returned: always
+            type: str
+            sample: "2023-11-06T13:36:56+00:00"
         status:
             description: Status of the server
             returned: always
@@ -366,6 +371,7 @@ class AnsibleHCloudServer(AnsibleHCloud):
         return {
             "id": to_native(self.hcloud_server.id),
             "name": to_native(self.hcloud_server.name),
+            "created": to_native(self.hcloud_server.created.isoformat()),
             "ipv4_address": ipv4_address,
             "ipv6": ipv6,
             "private_networks": [to_native(net.network.name) for net in self.hcloud_server.private_net],

plugins/modules/hcloud_server_info.py

@@ -62,6 +62,11 @@ hcloud_server_info:
             returned: always
             type: str
             sample: my-server
+        created:
+            description: Point in time when the Server was created (in ISO-8601 format)
+            returned: always
+            type: str
+            sample: "2023-11-06T13:36:56+00:00"
         status:
             description: Status of the server
             returned: always
@@ -167,6 +172,7 @@ class AnsibleHCloudServerInfo(AnsibleHCloud):
                     {
                         "id": to_native(server.id),
                         "name": to_native(server.name),
+                        "created": to_native(server.created.isoformat()),
                         "ipv4_address": ipv4_address,
                         "ipv6": ipv6,
                         "private_networks": [to_native(net.network.name) for net in server.private_net],