Handle specific wavelength constraint in service create

The ability to set a service according to a specific constraint on a wavelength to be used has been expressed several time for the purpose of demonstration.
Unfortunately, this possibility is not offered through regular RPC of OpenROADM service model. However a work around exists
Propose a simple solution based on the use of controller-customization module. By providing information on Spectrum filling rules (through openapi), it shall be possible to specify for a specific customer a restricted spectrum to be used. The code shall leverage this possibility implementing in the postAlgoValidator a check of rules that may apply to fill the spectrum