Refactor Ramsis.IO

@sarsonl I have a suggestion:

Since we decided, on using the ramsis.datamodel classes throughout the indu/ramsis ecosystem, we could also use the ramsis.io module throughout more of the packages.

My current use case would be to use the ramsis.io HYDWS serialization/deserialization code in the sfm_models repository to work with the hydws data.

Referring to my wiki post this code would clearly go inside the ramsis.datamodel ecosystem. I would even suggest keeping it in the same repository as ramsis.datamodel but I would welcome it if we discussed this more in person!