Execute integration tests in CI

[jlegrone]

This PR

• Runs docker and kubernetes driver integration tests (using kind for kubernetes environment setup)
• Configures the azure pipeline to always report test results and coverage, even on failure
• Increases test code coverage in CI for the driver/docker package from 0% to 62%, and for driver/kubernetes from 21% to 68%.

See new coverage reporting here: https://dev.azure.com/deislabs/cnab-go/_build/results?buildId=4231&view=codecoverage-tab