Allow configuring SecurityContextRepository for BasicAuthenticationFilter

[rwinch]

We should allow configuring SecurityContextRepository on BasicAuthenticationFilter so that users do not need to rely on SecurityContextPersistenceFitler. Users that want BasicAuthenticationFilter to use a custom repository right now can do this:

http
	.httpBasic(b -> b.addObjectPostProcessor(new ObjectPostProcessor<BasicAuthenticationFilter>() {
			@Override
			public <O extends BasicAuthenticationFilter> O postProcess(O filter) {
				filter.setSecurityContextRepository(new HttpSessionSecurityContextRepository());
				return filter;
			}
		}));

However, it should be easier to configure with an explicit option.

[evgeniycheban]

Hi, @rwinch @jzheaux I'd like to work on it.

[evgeniycheban]

Hi, @rwinch @jzheaux I've created a PR that adds a new method
securityContextRepository(SecurityContextRepository securityContextRepository) that can be used to customize it.