Allow previously submitted samples to bypass local validation

[lheisler]

For the analysis.xml, if I provide a alias that already exists for the sample, the sample information won't be submitted. An INFO message is returned indicating that the alias already exists
eg
sample with alias 'PCSI_0001_Pa_P' already exists in 'SUBMITTED' status, not submitting.

However, there is still an attempt to do local validation on the sample metadata, and this fails if certain fields are not provided.

I'd recommend including a field in the yaml where one can explicitly indicate that the sample already exists at EGA. This should result in local validation not being required for the sample metadata.

This may require follow up during submission to EGA, to ensure that the Alias does actually exist.