Add the option to have the storage level plot in p.u.

[datejada]

What and Why

For some storage assets, such as batteries, the storage level is commonly shown as state-of-charge (SoC) per unit (p.u.). So, for the plots of energy storage, we need an option to normalize or not normalize this result for plotting.

Possible Drawbacks

N.A.

Related Issues

No response

[clizbe]

Hold off making new plots in TulipaPlots - do #36.