WriteEngine code must use unsigned int to store column width

WE uses int to store column width that contradicts with the fact that column width is always positive.
struct ColStruct defined in writeengine/shared/we_type.h must use unsigned uint32_t to store the width. This affects some interfaces in at least WE code. One needs to find the interfaces effected in WE and other potential consumers of the WE code, e.g. DMLProc, DDLProc.