tools/kas-runner: Add --dry_run

The dry_run option disables external effects (such as creating
directories) but still logs the messages these effects would
create. Note some messages cannot be logged as they are reliant on
external effects.

Some external effects have had message added even outside of dry run
such as created directories.

Extra logging has been added that dispay details about the program
and arguments provided.

Issue-Id: SCM-3900
Signed-off-by: Joel Goddard <joel.goddard@arm.com>
Change-Id: I28a8ecc708d571027c0a2f89648e422c8052a2c8