shed: command to list duplicate messages in tipsets (steb)

[Stebalien]

Modification of #5841.

This one:

1. Let's you specify a start/stop height.
2. Prints out ndjson to stdout, and status/errors to stderr.
3. Prints one entry per set of duplicates.
4. Allows filtering messages by method number.
5. Allows configuring the number of threads.

Usage:

> cd cmd/lotus-shed
> go build
> ./lotus-shed audits duplicate-messages --start=148888 | tee output.ndjson

That will walk back to the mainnet epoch and write the results to stdout and output.ndjson.

TODO

• Make it possible to start at some height.
• Make it faster (parallel fetch and/or direct datastore access)?
• Make the method number filter customizable.
• Add better docs

[Stebalien]

I sincerely apologize for the git commit messages, I needed to send the code to a different machine for testing, and got tired of writing nice git commit messages. I'll rebase/squash later but don't want to mess with history right now.

[Kubuxu]

@Stebalien for this I use git over ssh with bare repo on the other side and one working repo.
So for example:

devbox1> git init --bare ~/lotus-bare
local> git remote add  devbox ssh://devbox1/~/lotus-bare; git push devbox master
devbox1> git clone ~/lotus-bare ~/lotus

Then if you want to push some branch you push to devbox1 and in ~/lotus dir in devbox you just pull and check it out.
The bare repo in the middle is there because you cannot push to checked out branches.

[arajasek]

LGTM, maybe confirm it works with latest changes.

[Stebalien]

confirm it works with latest changes

Done. I've also added support for {exclude,include}-{from,to} (which also seems to work).

[Stebalien]

(going to assume this is good to go, it's just a shed command after all).