[FEATURE]: Refactor default_values

[willu47]

Feature Request

There is no reason to "read in" default values in the ReadStrategy subclasses as this information is now stored in config.

Is your feature related to a bug?

No response

Suggested Solution

This functionality can be removed, and the ReadStrategy.read() method can return just the data rather than the tuple of data and default values.

The WriteStrategy does require default values if the write_defaults flag is set to True. So we can move the get_defauylts method over to the write strategies.

Additional Info

No response