JDBC sampler : Add hashing of Data to avoid storing all output into memory when result is arbitrarily large

**Nathan Bryant** ([Bug 41921](https://bz.apache.org/bugzilla//show_bug.cgi?id=41921&redirect=false)):
JDBCSampler (and I presume other samplers) store all the output received from
their test action. example:

Data data = getDataFromResultSet(rs);
res.setResponseData(data.toString().getBytes());

This is poor software design because the data could be arbitrarily large and
fill memory. It is causing OutOfMemoryErrors for us, even with not very many
threads. This is major or even critical because it prevents JMeter from being
used to generate significant load. All samplers should be rewritten to just
build an MD5 hash iteratively. The hash should be updated one buffer or row at a
time instead of in bulk.

OS: All

Start with JDBCSampler and the getDataFromResultSet flow described in the issue, including res.setResponseData. Trace how result data is accumulated and identify the affected samplers; done means large results no longer require storing all output in memory and are processed incrementally into an MD5 hash.

Written by the indexing model from the issue text.