Add source location to conditional statements

[andsel]

With #16322 was fixed the evaluation of conditional statement expression so that in case of error, like comparing string with integers, the pipeline doesn't crash, but simply log the problem and drop the offending problem.
In complex pipelines with many conditional it's difficult to go back to the impacted condition, so the log (and also the DLQ event when available) should contain a code reference to the if.

The feasibility of such feature was discussed in the comment