Allow http basic auth to be configured using nested builder

[eleftherias]

Support nested builder

Currently HTTP basic authentication can be configured in the following way.

http
	.httpBasic()
	.realmName("Realm");

We should allow configuration using a nested builder, as follows.

http
	.httpBasic(httpBasicConfig -> httpBasicConfig.realmName("Realm"));

The remaining methods should also be available in the nested builder, authenticationEntryPoint, authenticationDetailsSource.

Remove need for and()

Any subsequent configurations to HttpSecurity will not need to be chained using and().

http
	.httpBasic(httpBasicConfig -> httpBasicConfig.realmName("Realm"))
	.cors();

Nest disable()

HTTP basic authentication should be disabled using a nested builder as well

http
    .httpBasic(HttpBasicConfigurer::disable);

note: HttpBasicConfigurer may not be the appropriate class name.

[rwinch]

To keep things simple I'd say we should hold off on httpBasic(HttpBasicConfigurer::disable) since users will be able to do httpBasic(httpBasicConfig -> httpBasicConfig.disable()).

[eleftherias]

@rwinch I believe those are equivalent (assuming that we continue to use the HttpBasicConfigurer). The IDE will actually prompt you to replace the lambda with the method reference.

[rwinch]

Oops. My mistake. You are right :)