TAPI topology consolidation - step3

TAPI topology consolidation - step3

- transform the TAPI multi-layer topology abstraction to expose the
single 100G Transponder layer representing the connectivity between
100GE client ports of 100G Transponders connected to the ROADM
infrastructure. That gives a higher level of abstraction where the whole
otn-topology is abstracted into a single node with only its
corresponding onep.
- add UT to this specific topology abstraction

JIRA: TRNSPRTPCE-344
Signed-off-by: Gilles Thouenon <gilles.thouenon@orange.com>
Co-authored-by: Christophe Betoule <christophe.betoule@orange.com>
Change-Id: I048ff512a74cc5246eafda2cfb8444280b4c29f1