ability to use sequencer::{L1BlockInfo, VmId, SeqTypes} in third party rust code without dragging in most of libp2p and other obscure packages

[stskeeps]

[jbearer]

Hey @stskeeps. I don't think we'll be able to do this for Christmas, since we're in a feature freeze and trying to push out the next release. But we can absolutely make it a priority in the new year