Enums for sampleType, dataType, experimentalStrategy

[lopierra]

• Need to apply enums, but also rethink how dataType and experimentalStrategy are applied to cognitive, clinical, and other non-omics data
• Includes standardizing hyphenation, e.g. RNA-seq vs RNAseq
• Will affect Biospecimen, Datafile, Dataset, Assay metadata, etc.