Ldap credential resolver changes that delegates to an inner resolver for constructing principal out of the request.

Added minor improvements to ease the definition of search queries based on uid attr providers of person directory.
Cleaned up bean definitions to be able to properly run unit tests.
Merge branch 'feature-new-authn-api' into LDAP-CRED-RESOLVER
Credentials to Ldap Principal Resolver: Remove dependency to Person Directory's IUsernameAttributeProvider
Merge pull request #271 from mmoayyed/LDAP-CRED-RESOLVER

Ldaptive-based CredentialsToLdapPrincialResolver implementation