Add command line interface

Add a CLI that can be used to:

[x] create CoMIDs from a (JSON?) template
[x] create (unsigned) CoRIMs from a template and the file-system location of child CoMIDs and CoSWIDs
[x] validate CoMID
[x] validate CoRIM
[x] sign CoRIMs
[x] verify CoRIMs
[x] display CoRIMs content (as JSON)
[x] display CoMIDs content (as JSON)
[x] save CoMIDs and CoSWIDs embedded in a CoRIM to a directory as separate files

veraison / corim