Add subcommand for stack status

[jsoriano]

Add subcommand that prints the status of the stack managed by elastic-package stack, including the version started.

This subcommand could be elastic-package stack status.

[efd6]

It would be good if this also printed the version used when printing test outcomes (particularly for failures).

[mrodm]

It would be good if this also printed the version used when printing test outcomes (particularly for failures).

Adding that information in the test outcomes looks like is going to be helpful in case of failures. A new issue has been created in order to add it as part of the test output #922.

Currently, we're working to create the new command elastic-package status stack so it can be checked independently from tests to get the services running as well as their version and status (#917).