added setAuthorityResolver() methods to AsyncServerBootstrap / ServerBootstrap

[cdw8j]

I migrated a project from httpcore4 to httpcore5 just recently and when it didn't work, I had to dive into the httpcore5 sources to understand what was going wrong and that I need to create a custom RequestRouter with LOCAL_AUTHORITY_RESOLVER scheme to get the same behavior as before with httpcore4 just using simple ServerBootstrap methods. It is quite a pain to build the custom RequestRouter in the application itself, especially because this isn't really very well documented.

With this new setAuthorityResolver() method, the legacy behavior can be achieved by calling setAuthorityResolver(RequestRouter.LOCAL_AUTHORITY_RESOLVER) in combination with setCanonicalHostName("localhost") on ServerBootstrap or AsyncServerBootstrap .