buf beta price|stats feedback

[plaflamme]

Some useful things these commands could provide:

• provide a breakdown by package / module / file / etc
• provide the full list of messages / enums / methods being considered (beta price sometimes spits out a large number, which we can't easily cross-check)
• provide machine-readable output like json so these commands can be more easily integrated in other tools (say to report into cost attribution tools)

[bufdev]

Thanks for the feedback! buf beta price|stats was a quick and dirty implementation, but we can definitely improve it. We'll take all of this into account and see what we can do.

Of note: both commands are extremely simple, so if you're bored, feel free to get into them and send us a PR :-)