JsonConstructors does not work with System.Text.Json #10

When converting the features to System.Text.Json support, the JsonConstructors seem to fail, and no easy fix where found.

To make the serialization work, it was required to add a default empty constructor, which meant that object construction could be done in a way which is unintended.

For now this is the only solution, but finding a way to make the JsonConstructors work again would definitely be preferred.

Work:

• Make JsonConstructors work in the feature classes
• Remove the empty constructors on the features