tsk-51: Send message endpoint (#52)

Closes #51

Reviewed-on: phoenix/textsender-api#52
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

docs/swagger.yaml

@@ -154,6 +154,26 @@ definitions:
       message:
         type: string
     type: object
+  handler.SendInstantMessageRequest:
+    properties:
+      contact_ids:
+        items:
+          type: string
+        type: array
+      message_id:
+        type: string
+      user_id:
+        type: string
+    type: object
+  handler.SendInstantMessageResponse:
+    properties:
+      data:
+        items:
+          $ref: '#/definitions/message.MessageEventResponse'
+        type: array
+      message:
+        type: string
+    type: object
   message.Message:
     properties:
       content:
@@ -163,6 +183,21 @@ definitions:
       user_id:
         type: string
     type: object
+  message.MessageEventResponse:
+    properties:
+      id:
+        type: string
+      response:
+        items:
+          type: integer
+        type: array
+      scheduled_message_event_id:
+        type: string
+      sent:
+        type: string
+      user_id:
+        type: string
+    type: object
   scheduling.ScheduledMessage:
     properties:
       created:
@@ -266,6 +301,39 @@ paths:
       summary: Add contact
       tags:
       - contacts
+  /instant/message:
+    post:
+      consumes:
+      - application/json
+      description: Send a message without the constraints of scheduled messages (requires
+        JWT)
+      parameters:
+      - description: Send an instnt message
+        in: body
+        name: request
+        required: true
+        schema:
+          $ref: '#/definitions/handler.SendInstantMessageRequest'
+      produces:
+      - application/json
+      responses:
+        "201":
+          description: Created
+          schema:
+            $ref: '#/definitions/handler.SendInstantMessageResponse'
+        "400":
+          description: Bad Request
+          schema:
+            $ref: '#/definitions/handler.SendInstantMessageResponse'
+        "500":
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/handler.SendInstantMessageResponse'
+      security:
+      - BearerAuth: []
+      summary: Send instant message
+      tags:
+      - messages
   /message:
     get:
       consumes: