stdcm: make rolling stock labels shorter

[axrolld]

Who would benefit from this feature?

End users

What is this feature about?

In the list of rolling stocks here, the labels are very long, we can make them shorter by only displaying the reference of the rolling stock:

From the payload the front gets, display the "name" and "series" if it exists, "reference" otherwise.

{
        "name": "JT42US",
        "detail": "CLASS 66",
        "reference": "JT42",
        "series": "CLASS 66"
}

Why is this feature valuable?

This feature matters because it will make the rolling stock list clearer.