Additional parameter for charset encoding for directory datastore of shapefiles

Problem:
There is lack of parameter for attributes charset setting in directory datastore of shapefiles.
In case of a lot of shp, it is usefull to use DataStore instead of adding files one by one, where one's`ve got box to change charset encoding.
But there is no possibility to use such a parameter for directory of shapefiles datastore.
Probably default ISO-8859-1 is used in such a case.

Andrea Aime answer/comment:
The directory datastore has no such parameter.
Also, the datastore itself is not bound to shapefiles, so exposing
shapefile specific parameters would be a problem in the long run...

Either we make a special "directory of shapefiles" datastore that
only works with shapefiles, or we have to find some other way
to expose custom params, such as an open ended set of params that
the user provides and that are passed down to the wrapped datastore
(the directory one in the end only delegate to shapefile stores)
if the datastore exposes them.