Unify help messages handling

[kLabz]

Current situation is a bit weird, with different behavior:

• --help aborts immediately and goes through message reporting (and can use pretty errors etc)
• --version goes through message reporting (and can use pretty errors etc) and lets compilation continue (so it's added as a "normal" info message)
• --help-metas and --help-define directly print to stdout (kinda same for user variants)

Which means we can have these (click to expand)

But also this:

vs this:

And things like mix between raw stdout from --help-metas and message reporting from --version

With this PR, all of the above go through the same path, meaning:

• None of these would go through message reporting (bye "pretty" --version and --help)
• They will all abort after printing their content