cubicweb #1892461 rename config hostmapping to urlmapping [resolved]

The code in server/source/datafeed shows that methode replace() is called on the string representing the url. It is hence a urlmapping, not a hostmapping. Fix name of config file and names in the source.

prioritynormal
typebug
done in3.13.4
load0.100
load left0.000
closed by#70ea754d3e04 [server] host mapping is better named url mapping (closes #1892461)