cubicweb-rqlcontroller #5537346 RqlIOController.json does not handle properly the Content-Type header [validation pending]

I does not work for (valid) headers like:

Content-Type: application/json; encoding=UTF-8
prioritynormal
typebug
done in0.3.1
load0.500
load left0.000
closed by#c15c66e8cacc [views] better handling of the Content-Type header (closes #5537346)
patch[views] also handle the charset param of the Content-Type header (related to #5537346) [applied][views] better handling of the Content-Type header (closes #5537346) [applied]