Improving dryer loss assumptions

[nRiccobo]

Bug description
After reviewing the formulas and equations in cell.py, stakeholders indicated the the dryer_losses is too large for utility-scale systems. At large PEM scales (>1MW), thermal systems tend to be more sophisticated when it comes to drying and providing a higher hydrogen purity at the end of the conversion.

Expected behavior
When the dryer_losses are reduced more hydrogen is expected.