tools/kas-runner: Add kas-runner build script with developer features

This script is based on kas-ci-build with  addition of developer focused
features like a support for loading script parameters from a valid yaml file.
This file can be selected by setting
'--config=path/to/config.yml[:named-config]'.
The config file can contain more than one 'named-config'.
If no 'named-config' is specified, first one from the file is selected.

'--list-ci-build-targets' parameter is replaced with '--list-configs', that
will print '*-build' configs listed in '--config' file.

Below script parameters are not supported any more:
 (*) '--list-build-machines'
 (*) '--list-build-modifiers'

Issue-Id: SCM-2620
Signed-off-by: Kamil Dziezyk <kamil.dziezyk@arm.com>
Change-Id: I3860a8c4e93f26e4afb7f3f38c722c7e483a199d