Include route number in label of named route relations

[1ec5]

When labeling a route relation that has a name=*, include its network=* and route number (ref=*) for disambiguation. This is identical to 4856eef32b4b04ef40a86b64c98bb0e23cbb3305 by @k-yle. The only additional change is that we continue to show the name=* verbatim, without appending other details, if it looks like a PTv2-formatted description of the route. This should address the criticisms in #8707.

Fixes #8559.