Iss 536.1 utilize datasets abstraction

[nhaydel]

@gerrycampion i see you reviewed another PR related to dataset abstractions recently. This one is more up to date. I will address those comments here and merge this one once approved

[nhaydel]

@gerrycampion with regards to your questions:

1. Would it be a bad idea to add all of our custom operators that we make available in the engine, instead of just the dataframe operators? Since this is a big update but 90% of the way. - I'm not sure any other custom operators are useful outside of the dataframe operators

2 & 3. I will include the latest updates to the engine in this PR and in another PR I will remove the dataframe operators

[gerrycampion]

@nhaydel I'm looking at this: https://github.com/venmo/business-rules/compare/master...cdisc-org:business-rules:master#diff-0bc3d92118ee65c44b126d002359281aa3062be23a4b39ad0fc5444862558365

And I see custom StringType and GenericType operators

[nhaydel]

@nhaydel I'm looking at this: venmo/business-rules@master...cdisc-org:business-rules:master#diff-0bc3d92118ee65c44b126d002359281aa3062be23a4b39ad0fc5444862558365

And I see custom StringType and GenericType operators

Yes, those are not used by the rules engine and are carryover from forking the business rules repo

[nhaydel]

This PR addresses the following issues

https://github.com/cdisc-org/cdisc-rules-engine/issues/552

https://github.com/cdisc-org/cdisc-rules-engine/issues/551

https://github.com/cdisc-org/cdisc-rules-engine/issues/550

https://github.com/cdisc-org/cdisc-rules-engine/issues/549

https://github.com/cdisc-org/cdisc-rules-engine/issues/536

[nhaydel]

@gerrycampion thanks for those fixes!