feat(files, s3, expiration): add expires_after support to S3 files provider (#3283)

docs/_static/llama-stack-spec.yaml

@@ -2933,6 +2933,10 @@ paths:
         - file: The File object (not file name) to be uploaded.
 
         - purpose: The intended purpose of the uploaded file.
+
+        - expires_after: Optional form values describing expiration for the file.
+        Expected expires_after[anchor] = "created_at", expires_after[seconds] = <int>.
+        Seconds must be between 3600 and 2592000 (1 hour to 30 days).
       parameters: []
       requestBody:
         content:
@@ -2945,9 +2949,19 @@ paths:
                   format: binary
                 purpose:
                   $ref: '#/components/schemas/OpenAIFilePurpose'
+                expires_after_anchor:
+                  oneOf:
+                    - type: string
+                    - type: 'null'
+                expires_after_seconds:
+                  oneOf:
+                    - type: integer
+                    - type: 'null'
               required:
                 - file
                 - purpose
+                - expires_after_anchor
+                - expires_after_seconds
         required: true
   /v1/openai/v1/models:
     get: