@Bean AuthenticationManager/UserDetailsService to WebSecurityConfigurerAdapter

This simplifies things so that the WebSecurityConfigurer does not need
the getAuthenticationManager() or getUserDetailsService() methods. The fact
that the Adapter exposes them as a @Bean is an implementation detail since
it is technically a choice (i.e. not necessary to build springSecurityFilterChain).
#53 - Default WebSecurityConfigurerAdapter to autowire AuthenticationManager

Users can now allow the AuthenticationManager of a
WebSecurityConfigurerAdapter to autowire the AuthenticationManager
switch AuthenticationManager authenticationManager to void registerAuthentication

Switch WebSecurityConfigurerAdpater to now use void method for
AuthenticationManager since AuthenticationManager is optional (it can be
Autowired).