feat: add scale_factor and extend value_factor (next)

[X-Ryl669]

I've bootstrapped from PR #608 that was stalling.

I've fixed the remarks and fixed the implementation to also work with negative scale factor.
This allow to have a negative value_multiplier (for example, when injecting current in the grid) per entity and also a value_factor per entity.

I've also fixed the documentation.

This gives this:

where the blue graph is a negative valued since it's a production not a consumption:

[akloeckner]

Thanks for picking this up! From first sight and without testing, I'd suggest a few changes:

• PRs should target the dev branch as far as I understood. So, maybe rebase it to get it merged more easily...
• I believe, all computations can be delegated to computeState, by passing entity's index and using defaults (||). See computeUom for example. Right now, I believe, extrema are even scaled twice, i.e., when they are updated in updateExtrema and when they are displayed using computeState.
• Take care to use the right precedence: entity || card || default. Right now, it looks to me as if card settings would take precedence over entity settings in computeState.
• There are some typos resulting in multipler instead of multiplier.

[X-Ryl669]

1. The dev branch is lagging behind the master branch. Is it expected ?
2. That's what I did at first, but it doesn't work, since computeState is also called for non entity (like bounds). I could have broken this to 2 different functions but I think it's cleaner this way. Extrema aren't scaled twice, I'm just saving the value multiplier used when computing the extrema in the abs array, so I can compute their state with the appropriate multiplier when required.
3. You're right, I'll fix this.
4. I had a doubt about this from the initial PR which used multipler. TBH, I don't like the name "value multiplier" and I think "scale factor" would be better, what do you think ?

[X-Ryl669]

Closed to target dev branch in #884. I've renamed the variable to scaleFactor and changed the config order as expected.