Move pekahi to a lib repository

go.mod

go.sum

pkg/pekahi/cert.go

pkg/pekahi/io.go

pkg/pekahi/json.go

pkg/pekahi/pki.go

pkg/pekahi/templates.go

pkg/pki/ca.go

pkg/pki/master.go

pkg/pki/node.go

pkg/pki/utils.go