Address tech debt: only export modified properties into code, and (somehow) use default not-set values taken as a snapshot at time of project creation.

[ntoll]

At the moment, when code is generated for the UI, all the properties of a component are exported as either the default values, or whatever the coder has updated them to be (despite most properties not being changed from their default values).

We need to work out what our desired behaviour is for this process.