Node: Fix version in the starting node event

What

Fixes the display of the node version in the logs when starting the node.

Why

It used to be

starting the Tezos node vOctez 0.0+dev

But it should be

starting the Octez node Octez 0.0+dev

It is ill-formed since the introduction of products in octez-version.

How

• Create pp_simple in lib_version.
• Use pp_simple in starting_node event.

Manually testing the MR

Run an octez node and read the logs.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR