Improve metadata CSV template values. (#2066)
Improve metadata CSV template values. (#2066)

When existing samples, use the sample's metadata.
When new samples, keep the template blank.

When in a context without samples (CSV instructions) keep example samples with generated metadata.
chanzuckerberg/idseq-web,chanzuckerberg/idseq-web,chanzuckerberg/idseq-web,chanzuckerberg/idseq-web,chanzuckerberg/idseq-web