Backwards compat check should enforce enums are not renamed

[asfimport]

Reporter: Alex Levenson / @isnotinvain

Related issues:

• ThriftRecordConverter throws NPE for unrecognized enum values (relates to)

_{Note: This issue was originally created as PARQUET-351. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
@isnotinvain, is this a blocker for the 1.9.0 release? If so, please add a blocker link to PARQUET-392. Thanks!