* feat(backend) Fix authentication in upload requests
Fix the way KFP API server authenticates pipeline upload requests.
We leverage 'isAuthenticated()` function which requires proper
initialization of the context object to include user identity.
* feat(backend): Add namespace field in pipeline upload swagger definition
Extend swagger defintion of the pipeline upload API with a namespace
parameter in order to support uploading namespaced pipelines.
* chore(backend): Generate Go & Python clients
Autogenerate the Go and Python clients after extending the swagger
definitions of upload pipeline APIs with a namespace field.