cubicweb #5204550 [web] Add datadir-url configuration option [validation pending]

[web] Add datadir-url configuration option

Makes it possible to use a different host for static data instead of ${base_url}/data

prioritynormal
typebug
done in3.21.0
load left0.000
closed by#8cc58e8ad72f [web] Add datadir-url configuration option (closes #5204550)
patch[doc] mention datadir-url configuration option in release notes [applied][web] add test for datadir-url option (related to #5204550) [applied][web] Add datadir-url configuration option (closes #5204550) [applied]