rewrite covidseq workflow

[boulund]

Import samples from Tecan file instead. Fetch data upon sample sheet generation from NPC covid_samples database instead of reading from UDFs.

[boulund]

Note that sample name conventions will need to change, as the information in the previous scheme is no longer guaranteed to be available at sample creation:

SAMPLEID_REGIONCODE_LABCODE_DATETIME

will be replaced with:

SAMPLEID_DATETIME

This introduces a potential issue since sample IDs are not guaranteed to be unique without region or lab code information. Not sure how we want to handle that at this time.