Cut off phpipam api calls from `phpipam_utils.py` to make it more plugins available.

[cmeissner]

Is your feature request related to a problem? Please describe. In the early beginning of this project we decided to put all api calls inside classes where all modules derive from. This was fine until we want to start developing plugins such as lookup and inventory plugins. This plugin classes can not be derived from PhpipamAnsibleModule or PhpipamEntityAnsibleModule.

Describe the solution you'd like Now it is time to create a module which provides a phpipam related classes and methods in a way we can use it for all kinds of plugins. After creating such a module we can use it for all our plugins and modules. Another benifit will be that we can hide handling of strange different api calls from the user but we provide a common way. See it like a layer of abstraction.