Unofficial regenerator capability support in YANG

Unofficial regenerator capability support in YANG

Some non-compliant Open ROADM devices propose an additional regen
identity 'if-OTUCn-ODUCn-regen' in the common Open ROADM YANG model
org-openroadm-port-types
Though this identity should have been advertised through a deviation,
this does not raise any compatibility problem with compliant devices.

This ideally temporary work-around proposes to integrate this unofficial
regen identity until a compliant solution is found.

JIRA: TRNSPRTPCE-532
Change-Id: Ib63b8fb67e7afbf0889eb1916c132d8058df540e
Co-authored-by: Guillaume Lambert <guillaume.lambert@orange.com>
Signed-off-by: guillaume.lambert <guillaume.lambert@orange.com>