Product Ingestion Generated SDK (vendored_sdks)

Implement an SDK for the new [Product Ingestion API](https://learn.microsoft.com/en-us/azure/marketplace/product-ingestion-api).

## Design
- Generate model from JSON Schema definitions (published source)
- Implement client code generation or a single generic client that accepts any model, exposing standard operations/verbs

### Model generation

Approximate process to implement:

1. store all URLs of the schema files
2. Download all
3. rename each file to the name of the specific schema using $id (regex capture name)
4. move file to the folder, named the version from $id
5. replace snakecase with underscore in file name
6. go through each file, and...
- add title attribute with Pascal case of the name of the schema
- find the $ref values and replace with local reference instead of URI
- remove $defs attribute