Sqoop2: Equals operator abuse in MInputs

Currently the equals operator (=) for MInput objects is being used to compare the structure of two MInput objects but not their values. While this definition of "equals" is useful in the Repository, it makes it difficult for us to perform true comparisons between two MInput objects and may hide bugs in tests.

Perhaps the current definition of equals should be renamed to something like `equivalentStructure` and we should implement true equality for the equals operator.