feat: Update swagger to openapi 3.0.4, update request payloads with examples (#11533)

# Pull Request Template

## Description

Updates the public swagger spec to be OpenAPI 3.0.4 compliant. Regarding
#7893, I'm investigating the use of
[oas_rails](https://github.com/a-chacon/oas_rails) to auto-generate the
documentation along with correct expected payloads.
Mostly fixes #10531, related to #7893

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

Copied spec into swagger editor, reviewed outputs:

![openapi](https://github.com/user-attachments/assets/bd43f895-74bb-4373-ba6d-c5b190b699dd)

Note that this shows two errors with the `DELETE` endpoints as
technically these should not have a `requestBody` - in which case we
should be making use of another HTTP verb or another endpoint.

## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Daniel Jimenez <devildan.knex@gmail.com>
Co-authored-by: Daniel Jimenez <daniel.jimenez@spark64.com>

swagger/definitions/resource/extension/contact/conversation.yml

@@ -6,17 +6,48 @@ properties:
       sender:
         type: object
         properties:
+          additional_attributes:
+            type: object
+            description: The additional attributes of the sender
+          availability_status:
+            type: string
+            description: The availability status of the sender
+          email:
+            type: string
+            description: The email of the sender
           id:
             type: number
             description: ID fo the sender
           name:
             type: string
             description: The name of the sender
+          phone_number:
+            type: string
+            description: The phone number of the sender
+          blocked:
+            type: boolean
+            description: Whether the sender is blocked
+          identifier:
+            type: string
+            description: The identifier of the sender
           thumbnail:
             type: string
             description: Avatar URL of the contact
-          channel:
-            type: string
-            description: Channel Type
+          custom_attributes:
+            type: object
+            description: The custom attributes of the sender
+          last_activity_at:
+            type: number
+            description: The last activity at of the sender
+          created_at:
+            type: number
+            description: The created at of the sender
+
+      channel:
+        type: string
+        description: Channel Type
       assignee:
         $ref: '#/components/schemas/user'
+      hmac_verified:
+        type: boolean
+        description: Whether the hmac is verified