HPCC-10366 Add parallel query support to regression suite

Part - 1:

Add parallel query support with --pq parameter for run mode. It uses threads
to accelerate test cases execution.

Sort result log when --pq used and test cases don't finished in same sequence
as they started.

Add 'all' parameter to query mode to run ECL program on all target clusters.

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