Support reading Decimal/Decimal128/Decimal256 over Flight

[nbauernfeind]

As a user, I would like to be able to work with fixed point decimal types over Arrow Feather and Flight.

We might not be able to write until we are able to attach properties to the column that further clarify which Decimal type is sufficient (w.r.t. avoiding loss of precision) to write to the wire. See #3455.