Update/Add unit tests Post Poly2 Update

[sedavid01]

Goal: Update the unit test suite in the R package to account for the updated implementation of the poly2 model.

Needs:

• New test fixture from HTTR (ensure that these are masked); gene level, signature level - updated data from HTTR team (Contacts: Logan/Derik); may also want to include some additional poly2 cases (both monotonic and biphasic)
• New test fixture from HTPP (ensure that these are masked); feature level, category level, and global level - updated data from HTPP team (Contact: Derik); may also want to include some additional poly2 cases (both monotonic and biphasic)
• Update the non-datastream specific unit tests that no longer work due to implementation of poly2
• Extend unit tests to account for implementation updates in poly2 and greater set of optional cases
• Investigate whether there is a way to handle the anticipated warning messages from poly2 in the unit tests - if so implement work around in the unit tests