Add gap analysis capability to the frontend

[northdpole]

currently, our backend allows for performing gap analysis exercises between any two standards we support. we should:

1. revisit the implementation with some GRC people and validate that our implementation of gap analysis is correct.
2. add a frontend feature that allows for gap analysis to be performed from the frontend

[GameDevImp]

I'm on the GRC side and would be interested in assisting with / testing this functionality.

[northdpole]

Sounds great! Currently you can test gap analysis on this url, it's just an experimental deployment so don't expect any reliability but your feedback is appreciated

[robvanderveer]

@northdpole done?