Optionalrecord: any
the registration: name, identity, certificate subject, thumbprint, authenticated, notify URL, bias, resource, version and description
{ ok: true, name, created }, or { ok: false, why } carrying
its error code when there is no directory, no usable name or the
directory refuses the entry
Registers a remote PEP, or updates its row when it re-registers.
A re-registration keeps the registration date, the counters, the sync token and a disabled state.