Update package name and CLI

This release includes updates in naming, workflow, and nlp model handling.

• naming
  • Update the package name from nlpviewer_backend to stave_backend.
  • Update CLI subcommand stave load to stave load-samples
  • Update the CLI flag --load to --load-samples.
• workflow
  • Replace Travis CI test with GitHub workflow.
• nlp model
  • Use RemoteProcessor to load NLP pipeline from remote service instead of directly importing specific processors from forte.
  • Add a new optional field remoteConfigs in default project configuration for users to configure remote service.