Motivation
In netty 5 we can use java.util.Base64 which is simpler/faster for some
purposes than netty's own ByteBuf-based Base64 utilities. This covers a
couple of additional places to the one changed in #8837
Modifications
Modify HttpProxyHandler and HttpProxyServer classes to use
java.util.Base64 instead of
io.netty.handler.codec.base64.Base64 (latter is a test
one).
Result
More efficient base64 processing in proxy impl.
d539864f83