Poor performance of SAP RFC V2

[marcinpurtak]

The SAP RFC V2 connector is a legacy code migrated from viadot 1.0.
This code bypases the SAP BBP_READ_TABLE func limitation for length of the columns however there is a lot of for loop in this code which are not memory efficient. Additionaly there is a legacy function to check if additional separators exists in the data which is not used but it slows down the processing.

Steps to finish:

• Switch from regular for loop to generator approach
• Remove code responsible for separators check