cubicweb #1951819 change entities.asource column size [validation pending]

it must be varchar(128) and not varchar(64) since it is meant to hold CWSource.name

priorityimportant
typebug
done in3.14.4
load0.200
load left0.000
closed by#14c52c5ee706 [entities system table] change asource and source column size (closes #1951819)