Add Italy network logic

[nvkelso]

We have shield artwork for Italy's roads, but no network values because the data is sparse there so we need to compute values.

We're missing handling for:

• IT:RA Raccordo autostradale (sometimes these are blue) - translated as motorway connection. Not clear if this is IT:B-road below.
• IT:SP - strada provinciale (same as IT:SR) - provincial road
• IT:SR - Regional road
• IT:SS - Strade Statali (same as IT:SR) - State highways

We already handle these, via data values:

• IT:A-road - Italy A-roads for national autostradale
• IT:B-road - Italy B-roads