This commit changes the `HandlerStrategies` and `ExchangeStrategies`
builders to use the `CodecConfigurer` for configuring Decoder|Encoder
and HttpMessage[Reader|Writer]. Other classes that use `CodecConfigurer`
have also been changed to reflect the refactoring to interfaces.
This commit also removes the ExchangeStrategies methods that take an
application context, as it was too naive approach to simply look up
every message reader and writer in the context.
Issue: SPR-15415, SPR-15435
dc279d839b