EARLY MERGE: Update ConstructionSystem to support invisible layers that are between visible ones

[mqole]

About the PR

early merge of space-wizards#40668
imp comments added

Why / Balance

required to fix issues in #3721

Requirements

• I have read and am following the Impstation Design Principles and Coding Standards.
• I have added media to this PR or it does not require an ingame showcase.

[dayn-e]

The way I'm reading this is visibleLayers is meant to be an index for the list of layers so that it applies the shade, sprite etc for every valid layer. For this reason I'd suggest renaming it to something like visibleLayerIndex.

[dayn-e]

This will cause a desync of your index counter and the layer the loop is on, meaning it might apply to an incorrect layer.

Click here for an example if you don't get what I mean.

For example say we have an item with three layers.

Layer 1 - index 0 (tracked by visibleLayers) - valid
Layer 2 - index 1 - invalid
Layer 3 - index 2 - valid

What would happen in this case is since visibleLayers is incremented at the end of the foreach, which is skipped in both these checks, means that after Layer 2, the variable will be at 1, while the loop is looking at Layer 3. If that were to happen, then the rest of the function would try to apply everything to the invalid layer.

Suggested change

	if (!layer.Visible || !layer.RsiState.IsValid)
	continue;
	var rsi = layer.Rsi ?? source.BaseRSI;
	if (rsi is null || !rsi.TryGetState(layer.RsiState, out var state) || state.StateId.Name is null)
	continue;
	if (!layer.Visible || !layer.RsiState.IsValid)
	{
	visibleLayers++;
	continue;
	}
	var rsi = layer.Rsi ?? source.BaseRSI;
	if (rsi is null || !rsi.TryGetState(layer.RsiState, out var state) || state.StateId.Name is null)
	{
	visibleLayers++;
	continue;
	}

[mqole]

closing per maints discussion