HPCC-10107 Csv auto discovery should work with utf8 files.

Temporarily clone the CSV record processing code from CCsvPartitioner
into CUtfPartitioner class to implement record structure discovery for
UTF encoded files.

The final solution will be implemented in HPCC-10232 - Refactoring CSV record
processing and record structure discovery issue.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>