UX - Draft performance measures script for Viewer integration

[bstabler]

For the Viewer integration, we need to draft a performance measures script that reads existing HDF5 output files for an input set of scenarios and writes a summary performance measures file for input to the Scenario Viewer. Since the models are not yet fully implemented, it will simply read the HDF5 output files and write fake data for all the existing fields required by the Viewer. This will allow us to test and complete the Viewer integration while the models are being implemented.

[bstabler]

See UI Design as well

[bstabler]

This relates to #154 since we need an efficient way to query multiple datastores.

[bstabler]

This is done in draft form, see https://github.com/gregorbj/VisionEval/blob/add_scenario/sources/modules/VEScenario/R/ScenarioResults.R