aaa: Extracted session management outside of AdBroker package

a. All LdapBroker commands that are not LdapAuthenticateUserCommand
should use the user associated with the domain -
no need to session management here (the user is kept at
UsersDomainsCacheManagerService)

b. For the LdapAuthenticateUserCommand - the code is extracted to the bll
LoginBaseCommand

Topic: AAA
Change-Id: I82003f1b91847d3f75d99e2b02eb238ab050d62e
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>