Update workflow schema to support matching on organism

[NoopDog]

Add approch from parent ticket #355

From #355:

"As for how to map them in the schema, I'd like to be able to pick an arbitrary ncbi tax Id and let its children use the workflow too. I'm not convinced we need the root node toggle thing, provided everything won't break if I pass a tax id for a genus or some other non-organism thing. (Note: the arbitrary tax ids in this context seem an important thing to qc via an automated script and report)"

Approach

1. Add a field to the schema "tax_id" with a description and adjust he validations accordingly. The id can be at any level. e.g. kingdom, phylum, class, order.."
2. On the organisms page, we will check that any organism-specific restriction on a workflow matches the given organism or any of its ancestors.
3. Update the workflow matching on the assembly detail page to match a specific organism and descendants.