HPCC-9867 CSV spray incorrectly splitting records with nested quotes

Clone and adapt CSVSplitter::splitLine implementation (from csvsplitter.cpp)
into CCSVPartitioner::getSplitRecordSize() to fix quote handling problem.

Implement missing ESCAPE handling code for CCsvPartitioner class.

Signed-off-by: Attila.Vamos <attila.vamos@gmail.com>