Make TimeVaryingArray and TimeVaryingScalar immutable. This is with a view to make the full model config immutable, which makes it possible to safely cache computations inside the model without worrying that a user has modified the field of eg. TimeVaryingArray, which is undetectable from a higher-level without major overhead.

Make TimeVaryingArray and TimeVaryingScalar immutable. This is with a view to make the full model config immutable, which makes it possible to safely cache computations inside the model without worrying that a user has modified the field of eg. TimeVaryingArray, which is undetectable from a higher-level without major overhead. #4582