Add ordering to output objects

[bfirsh]

Inputs are ordered, but outputs are not.

[zeke]

zeke/cog-haiku#12

[zeke]

The order is still intact in Cog's OpenAPI schema:

But not in the schema (nor the prediction object) in replicate-web, which looks to be alphabetical:

[zeke]

In replicate-web, the order of the outputs in the properties is reversed:

postgres=# select openapi_schema->'components'->'schemas'->'Output'->'properties' from models_version where docker_image_id='9d45ce800c36226fa0190021cc70ce6bbb64dce6ff71c70eb2acf11c45fd2635';
                                                                          ?column?                                                                           
-------------------------------------------------------------------------------------------------------------------------------------------------------------
 {"seed": {"type": "integer", "title": "Seed"}, "text": {"type": "string", "title": "Text"}, "image": {"type": "string", "title": "Image", "format": "uri"}}
(1 row)

I think we need to solve this by adding x-order properties to each output object, like we do for Input in Cog.

[zeke]

Related: go-openapi/spec#24

[zeke]

@chenxwh ran into this again today.