build: Restore compilation output for './ns3 run' command

I had requested to change the behavior of ./ns3 run to hide compilation output, and also to hide the trailing statements of Finished executing cmake....

I think that in hindsight, it is better to keep the output so that the user can be reassured that the rebuild happened (if a file was touched). We have the --no-build option to suppress build system output (i.e., --ho-build will not attempt a build and will not print out the "Finished executing ..." statements).

I do not think that ./ns3 run needs to print out the cmake task lines, just the output of the underlying build system (ninja or make).

I'm just posting this here in case anyone objects to going back to the way Waf handled it.