Support for Artifactory, Cloudsmith, Quay, and generic Docker registries

[gadkins]

Task

Expand Uffizzi's support for more container registries, particularly these popular ones:

• JFrog Artifactory
• Cloudsmith
• Quay

We can support these and more by implementing support for Docker Registry HTTP API

To support generic docker registries, we should add docker-registry subcommand to uffizzi connect.

Example use

$ uffizzi connect docker-registry 

Input data can be read from these environment variables:

• DOCKER_REGISTRY_URL
• DOCKER_REGISTRY_USERNAME
• DOCKER_REGISTRY_PASSWORD

Options for connect:

### OPTIONS
       -r, --registry=<registry>
              URL of the service.

       -u, --username=<username>
              Username for the service.

       -p, --password=<password>
              Password for the service.

JFrog Artifactory](https://jfrog.com/artifactory/) example:

uffizzi preview create with this compose file:

services:
  web:
    image: antlu.jfrog.io/default-docker/antlu/hello
    command: ["python", "/code/manage.py", "runserver", "0.0.0.0:8000"]
    ports:
      - 8000:8000