cardano-ping: report user friendly error on misconfiguration

[coot]

Changelog

- description: |
    Show user friendly warning when `cardano ping` command is misconfigured.
# uncomment types applicable to the change:
  type:
    - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

Fixes #49.

How to trust this PR

When using unix sockets, cardano-ping can only query tip or supported
versions, since the node-to-client protocol doesn't include keep-alive
mini-protocol.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[carbolymer]

Looks good, few remarks with regards to naming. Thanks.