Cpacspy

- Add some cpacsfunctions
- Add some tests

- add a new function "add_value" which allows to add value to CPACS (and create all the xpath if not exit already)

* Add rotorcraft configuration
* fix import bug

* Typo ref_lenght -> ref_length

* Accept either Path of str when opening or saving a CPAS file

* Update conda environement

* fix import

- Adapt paths to run on Windows

This version is based on "cpacscreator v0.1" and not anymore on "tigl3" because some function are missing, will be updated when both library will be merged (https://github.com/DLR-SC/tigl/issues/831).

New features:
- New functions for aeromaps
- 'ref_wing_uid' added to the Aircraft class

Improvements:
- 'get_value' and 'get_value_or_default' functions
- Add and improve codecov, flake8 and tests