Table Manger definition lookup is brittle

[jmthomas]

TableManager will only lookup a definition if the filename has a single underscore followed by _def.txt, e.g. MCConfigurationTable_def.txt. Some customers like to use underscores in their table names like MC_configuration_table_def.txt which will break our lookup logic. This should be more robust to lookup a file based on whether the binary extention is .bin or .tbl and the config definition has _def.txt or simply matches the binary filename.