Protocol Parser should allow for code to be provided before the decode is invoked

Some remote protocols may want to have some code to be invoked before decode. For example some protocols must parse commands in the order they are received and make sure the commands. In this case a simple way to implement this is by disabling auto read on the netty channel and not parse the next command until the prior one completes.

The simplest way is to add a special named rule that the code can be written before decode.