tools/kas-runner: Refactor to allow config file validation

Added classes to manage settings that can be set from both
command line arguments and config files. Each setting is
only defined once. Default config has been merged with new
settings classes so settings are defined in one place.

Settings can have optional resolve functions for extra
processing and validation. Internal settings are excluded
from command line and config files.

ArgumentDictionary is replaced with RunnerSettings which
provides helpers for validation and resolution of configs.
Setting values are now accessed as variables on the
RunnerSettomgs.

Note: Arguments previously set with the format '%(arg)s'
should now use '{arg}' instead.
Note: Some logging has changed.

Issue-Id: SCM-3900
Signed-off-by: Joel Goddard <joel.goddard@arm.com>
Change-Id: Iec9f418ad776e801470467a7f3aa16e546212b13