Where has it moved to?
It’s at UnityEditor.Rendering.HighDefinition.EmissiveIntensityUnit in v7.1 - Redirecting to latest version of com.unity.render-pipelines.high-definition
Hello,
Unfortunately, it has been moved to internal so you can’t access it anymore 
Here’s the definition of the enum: https://github.com/Unity-Technologies/Graphics/blob/master/com.unity.render-pipelines.high-definition/Editor/Material/ShaderGraph/Nodes/EmissionNode.cs#L12