MOA therapy unique contraint failed

[korikuzma]

{
        "name": "Selpercatinib",
        "type": "Targeted therapy",
        "strategy": "RET inhibition",
        "resistance": "",
        "sensitivity": 1
}

and

{
        "name": "LOXO-292",
        "type": "Targeted therapy",
        "strategy": "RET inhibition",
        "resistance": 1,
        "sensitivity": ""
}

normalize to the same concept normalize.therapy.rxcui:2370147. However, we create two separate Therapy objects in MoaTransformer with the same id="moa.normalize.therapy.rxcui:2370147", which fails to satisfy the DB uniqueness constraint.

This is similar to #409

[korikuzma]

Other conflicts:
Abiraterone acetate and Abiraterone resolve to rxcui:1100071
Rapamycin and Sirolimus resolve to rxcui:35302