Generate MySQL client config if service requires database

Generate MySQL client config if service requires database

Services that access database have to read an extra MySQL configuration file
/etc/my.cnf.d/tripleo.cnf which holds client-only settings, like client bind
address and SSL configuration. The configuration file is thus used by
containerized services, but also by non-containerized services that still
run on the host.

In order to generate that client configuration file appropriately both on the
host and for containers, 1) the MySQLClient service must be included by the
role; 2) every containerized service which uses the database must include the
mysql::client profile in the docker-puppet config generation step.

By including the mysql::client profile in each containerized service, we ensure
that any change in configuration file will be reflected in the service's
/var/lib/config-data/{service}, and that paunch will restart the service's
container automatically.

We now only rely on MySQLClient from puppet/services, to make it possible to
generate /etc/my.cnf.d/tripleo.cnf on the host, and to set the hiera keys that
drive the generation of that config file in containers via docker-puppet.

We include a new YAML validation step to ensure that any service which depends
on MySQL will initialize the mysql::client profile during the docker-puppet
step.

Change-Id: I0dab1dc9caef1e749f1c42cfefeba179caebc8d7