Propagate more information about transceiver failures

[bnaecker]

swadm reports information about transceivers, and will show some basic failure information if we can't read from the modules. For example:

root@oxz_switch1:~# swadm switch-port transceiver list
Port   State             Reset  Interrupt  Power  Power control  Vendor  Part No.  Serial No.
qsfp0  faulted (Failed)                                                            

However, we added much more fine-grained error information to the transceiver-control protocol used under the hood to talk to the SP about the transceivers. We can see this with xcvradm for example:

root@oxz_switch1:~# xcvradm -i sidecar0 -t 0 vendor-info
Port Identifier               Vendor           Part             Rev  Serial           Mfg date
Some operations failed, errors below
Port Error
   0 Hardware error accessing module 0: The module stretched SCL too long

We need to go back and expose those error details through the Dendrite API and to swadm as well.