Improve the PVMT API

[ylussaud]

The API should manipulate PropertyValue instead of string this way one could easily change the value of an existing PropertyValue. We should probably also add an API to set a property value.

• get_p_v_names(elem: CapellaElement) -> Dict[str, str]
  • return a map from group name to value name
• is_p_v_g_defined(elem: CapellaElement, PVGName: str) -> bool
• is_p_v_defined(elem: CapellaElement, PVGName: str, PVName: str) -> bool
• get_p_v_group(elem: CapellaElement, PVGName: str) -> PropertyValueGroup
• get_p_v_value(elem: CapellaElement, PVGName: str, PVName: str) -> PropertyValue
• set_p_v_value(elem: CapellaElement, PVGName: str, PVName: str, value: PropertyValue)

[ylussaud]

It should also be easy to retrieve a domain an access its types and create new properties and values for them.

[ylussaud]

An interesting discussion from the forum.