Improve aron dict to dataclass

Required changes to support ARON ice to python/dataclass conversion for types such as NamePhrase

• Support typing.Union (thereby, typing.Optional)
• Use from_aron_ice() function if target type supports it

Also: Add test utilities for C++ to python conversion matching interface added in robot-api!325 (merged)

Related to https://git.h2t.iar.kit.edu/sw/armarx/speechx/-/merge_requests/17