Add OTN links support in TAPI topology

Add OTN links support in TAPI topology

- Add OTN OTU4 and ODU4 links in TAPI topology. Replace 2
  unidirectional OTU4 links in OpenROADM otn-topology by a single
  bidirectional Photonics link in TAPI. In the same way, replace 2
  unidirectional ODU4 links in OpenROADM otn-topology by a single
  bidirectional ODU link in TAPI topology
- add new Unitary tests for TAPI otn links
- add a new sample OpenROADM otn-topology XML file
  containing more nodes with OTN links as input for UTs
- adapt UUID creation to take into account new OTN topology context
- wait that the XML input file has been written in datastore before
  getting topology from it in UT

JIRA: TRNSPRTPCE-185
Signed-off-by: Gilles Thouenon <gilles.thouenon@orange.com>
Co-authored-by: Christophe Betoule <christophe.betoule@orange.com>
Change-Id: I5c762f30d3bd290b98d04d7f960fb1077be3a111
(cherry picked from commit a01f4032cd7dc71e3f047db5b3e2db77c4733b2c)