Remove inline CAS segment, update CAS.xml

There was an incomplete CAS segment defined inline as part of 835.xml;
this is removed in favor of the unadultered CAS.xml.

In addition, this updates the element names defined in CAS to better
align with the current 835-W1A1 schema.

ClaimAdjustmentReasonCode1 -> AdjustmentReasonCode1
MonetaryAmount1 -> AdjustmentAmount1
Quantity1 -> AdjustmentQuantity1

And so on.