ping: split the visual part of -f into a new option -.

From: Piotr P. Stefaniak <pstef_at_freebsd.org>
Date: Mon, 11 Apr 2022 18:36:41 UTC
Hackers,

In https://reviews.freebsd.org/D34882 I propose to split ping's option
-f into two options: one for flooding with ICMP (-f, no change in
behavior) and one for affecting the programs output (-., a new option).

That way we would be able to ping a host and not spam the terminal, and
no flooding would have to be involved. I've been doing this under Linux
as ping -fi1 host.

PS. In D32943, D32944, D32945 I implement the base64 command.

Piotr