CesiumRuntime requires Slate / SlateCore, but it is not listed as a dependency

[kring]

Our UScreenCreditsWidget, which is found in our CesiumRuntime module, uses Slate to display credits. But we're incorrectly only depending on Slate in Editor builds:

if (Target.bBuildEditor == true)
{
    PublicDependencyModuleNames.AddRange(
        new string[] {
            "UnrealEd",
            "Slate",
            "SlateCore",
            "WorldBrowser",
            "ContentBrowser",
            "MaterialEditor"
        }
    );
}

This is causing linker error in shipping builds on at least one user's system. It's not clear why it doesn't cause problems everywhere. The fix is to move Slate and SlateCore to the other list of PublicDependencyModuleNames in this file so that it's included as a dependency in all builds.

Reported here:
https://community.cesium.com/t/ue5-3-2-cesium-fails-to-package-for-windows-due-to-slate-errors/33661