Lacking form field definitions for Registry API createExtensionBundleVersion

The current swagger annotations for the 
createExtensionBundleVersion function in BucketBundleResource results in the form parameters for 'file' and 'sha256' being left out of the generated swagger api defenition for the /buckets/{bucketId}/bundles/{bundleType} endpoint.
 
By adding a 
ApiImplicitParams annotation for both these fields, swagger will correctly interpret these and add them as fields to the endpoint.
 
When generating swagger clients, this change is required to correctly support the necessary input arguments