[quick] Add grebe template: compare two gene sets for two terms

[cmungall]

Example driver: geneontology/go-ontology#20250

I'd like to compare two gene sets

• all genes directly annotated to T1
• all genes directly annotated to T2

Ideally I'd like 4 results - intersection, g(T1)-g(T2), g(T2)-g(T1), but this is harder to fit into the template system. But just getting genes in T1 but not T2 would be great. This is a simple boolean.

However, I think a template:

• T1: term1
• T2: term2
• S: species

And that returns all results from bioentity query with closure to T1 but not closure to T2

[kltm]

I think I get what you're getting at... this #605?