cubicweb-i18nfield #4508424 Rename Language into i18nlang [validation pending]

Language is en entity name too common to be used in such a cube

prioritynormal
typetask
done in0.1.0
load0.200
load left0.000
closed by#19c93eef382a [cleaning] rename `Language` into `I18nLang`
patch[cleaning] rename `Language` into `I18nLang` [applied]