Consider using Hermes instead of MrPowers _spark-fast-tests_ for dataframe comparison

## Background
In #1772 ( PR #1779), it was suggested to use Hermes to compare actual v. expected dataframes instead of MrPower's fast dataset compare.

At the of writing this issue, Hermes has not been considered unit-test-framework ready. Feel free to revisit the decision.
Commit https://github.com/AbsaOSS/enceladus/pull/1779/commits/6033d2908e543cd72248177bad60a25c20373b46 specifically shows the then-needed changes to switch the DF-comparing framework, so the information contained there might come in handy in the next iteration