Excel test datasets need a format for USDM json

[drewcdisc]

In order to support the USDM data source in the Rules Editor the excel test datasets should provide for a format catered to USDM json without the need for xpt extensions in sheet names.

[drewcdisc]

This issue has been split off of #218

[ASL-rmarshall]

Technically, this is still needed but it is a low priority