Added additionalProperties subfield to K8Slice Property field (#4)

[andreacv98]

Hi everyone,

With this PR you can finally add any custom field you want to the Flavor CR into the specific field Property of the K8Slice. With this change, FLUIDOS Node becomes more compliant to the REAR Protocol Data structure.

In particular, you now have an optional subfield in the Property field of the K8Slice flavor called "additionalProperties". It is a map of objects, not unmarshalled nor verified by the FLUIDOS node, so you can put any custom property you want, but remember that the FLUIDOS node will not process or take them into account.

Just to give you an example of a possible patch to the Flavor with this new field:

spec:
  flavorType:
    typeData:
      properties:
        additionalProperties:
          bandwidth:
            AZURE: 100ms

I hope the new changes are clear enough and useful for everyone. By the way, don't worry, nothing changes if you don't need the additionalProperties sub-field.

Thanks in advance for any feedback!

Andrea