Introduce handshake command + tighter ping UI

[smelc]

Changelog

- description: |
    Remove the `-u/--unixsock` option from `cardano-cli ping`,
    because it wasn't performing ping; only handshake.

    Add the `cardano-cli handshake` commands,
    that support both distant hosts (`-h/--host`, `-p/--port`)
    and local hosts (`-u/--unixsock`).
    Like its name suggests, `cardano-cli handshake` only does the handshake part of `cardano-cli ping`.
    
    Deprecate `cardano-cli ping`'s `-Q,--query-versions` flags.
    You should use the same flag with `cardano-cli handshake` instead.
    
    TLDR: if you were using `cardano-cli ping -Q`, use `cardano-cli handshake` instead.
    And don't pretend `cardano-cli ping` works on unix sockets.
# 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
  # - improvement    # QoL changes e.g. refactoring
  # - 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 [BUG] - cardano-cli ping --unixsock not sending pings #49
• UI was validated by @coot and @mkoura

How to trust this PR

• Execute cardano-cli handshake, witness it works
• Execute cardano-cli ping -u SOCKET, witness it doesn't exist anymore.

Checklist

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

[Jimbo4350]

This shouldn't be a separate command. It should live under the ping command as something like handshake-only.

[smelc]

We've settled for cardano-cli ping --handshake-only here on Slack.

[smelc]

Will likely be superseded by #524 in the end

[github-actions]

This PR is stale because it has been open 45 days with no activity.