Modernizing uca-phantom to latest GObject standards and practices

[gabs1234]

Main objectives

Not much is actually needed to be done. The task would mostly entail

• using GObject's net macro's for better typechecking, signal handling and error propagation.
• Use GObject's new type registration methods. Most notably the private structure ones
  These are currently not used.

important: check if updating uca-phantom to modern GObject will break compatibility with uca-camera. => I am reasonable certain that this is not an issue, but this should be sandbox-tested first.