Add a profiles arg to build.py to allow users to easily build common sets of images

As a time saver, I rarely build all images, and suspect other users are the same. Most often I just need to build the "core" images needed to deploy instances, e.g. nova,keystone,glance.

When specifiying the regexes for these, one must not only remember the associated services for the above such as mariadb, rabbitmq, etc., but also kolla "under the hood" services such as data and kolla-ansible.

Hence it may be useful to be able to define 'build profiles' for these common sets of images in the kolla-build.conf, e.g.:

[profiles]
minimal = data,kolla-ansible,rabbitmq,keystone,mariadb,nova,neutron,glance
swift = data,kolla-ansible,mariadb,keystone,swift

Then the user can run:

tools/build.py --profile swift

The regex functionality can be used in combination with the above, e.g. to build everything required for swift, but also cinder, one could do:

tools/build.py cinder --profile swift