Fix "Import column" stage to allow to properly validate numeric values

Data validation is extremely useful for any enterprise, but this stage is not working for numeric values, although it's the 'expected behaviour'. Validation for other data types already works as expected. But, not being able to properly validate numeric values, makes this capability almost useless. The « import column » stage - takes a FILLER field, which concatenates a list of data with delimiters, - splits the data regarding an interface contract which includes a structure and the delimiter value, - makes the structure with the interface contract structure. This interface contract structure have types - There is an OK link + a reject link. The reject link rejects all the data irrelevant with the interface contract structure  Ideal to make METADATA validation. But not only. But what is wrong with this stage, is in case of INTEGER or DECIMAL, instead of rejecting data in case there are ALPHA at the beginning and/or end of the field, the stage removes the ALPHA and keeps only what was integer inside the field, without notice. Truncation without notice cannot be considered ‘expected behaviour’. That’s not good at all. A stage can’t modify the data by itself with no warning and no possibility for the developer to catch the modification. That’s a HUGE bug. That’s true for a metadata validation usage, but also for any usage of this stage. For other types than INT / DEC, it seems to work properly