Add Pixi support

[Nicogene]

Task description

In order to ease the use of this repo it may be convenient to add pixi support, similarly what @traversaro did here:

• Add pixi support to permit local users to generated models robotology/icub-models-generator#261

or @martinaxgloria did here:

• Add pixi support to build and run IMU test robotology/icub-tests#71

Definition of Done

The pixi support has been added

cc @pattacini