HPCC-11485 Return same file data in WsDFU/DFUQuery & DFUFileView

For each logical file, both WsDFU requests should return the same
data. In this fix, both WsDFU methods call the same function to read
logical file information. The function is enhanced to handle both
WsDFU requests.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>