Bug 18564: Improve koha-common.cnf parsing to pick the mysql host

Bug 18564: Improve koha-common.cnf parsing to pick the mysql host

my koha-common.cnf is using this form:

[client]
host=db
user=root
password="move_rootpwd_to_dotenv"

this file is working has expected with mysql tools.

but koha-create parsing will not find the db host resulting in
koha-conf.xml containing no values in hostname element.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>