HPCC-8783 Refactor and split ccdserver.cpp

Split ccdserver into several logical parts. The part with all the
server-side activity code is still a little large.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #3981 from richardkchapman/roxie-split

HPCC-8783 Refactor and split ccdserver.cpp

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>