Add Principal Caching in MultiTenantUserManager

In most cache the MultiTenantUserManager does not need any specific caching :

• currentPrincipal is accessible inside the context
• JAAS provides a caching system

However, in some case, custom code can directly hit the UserManager and make several calls to generate new Principals.
In the context of MultiTenantUserManager this can lead to multiple queries.

To avoid that we wan to add cache.