Sina todo List from Initial PR

[bgunnar5]

This issue will contain several todos mentioned in the initial PR for adding Sina as an Axom component. They were put off for the future considering how large the initial PR was. Here is the todo list:

• With the completion of Move Sidre collections to core #1397 we should be able to use Sidre's collections for Sina's CurveMap and DatumMap. Relevant comment (on CurveSet) and relevant comment (on DataHolder).
• Several classes in Sina have optional units and/or tags that could likely be abstracted. Relevant comment.
• When Axom moves to C++17, refactor the four existing values of the Datum class (stringValue, scalarValue, stringArrayValue, and scalarArrayValue) to use std::variant. Relevant comment.
• Look into utilizing Axom's core Path class in axom/sina/core/File.hpp. Relevant comment.
• Investigate potentially similar logic between core/Annotation and sina/core/AdiakWriter. Relevant comment.
• Add tests for each Sina example. We'll likely want to test the validity of the output sina files against the sina schema for these examples. We might want to generalize the test_fortran_integration.py file and move it to axom/tools. Relevant comment 1 and relevant comment 2.
• Consolidate the NamedTempFile from Sina and the ScopedTemporaryFile class, and add it to the axom RAII utilities. Relevant comment 1 and relevant comment 2.
• Convert Sina's Fortran interface to shroud. Relevant comment.