Allow `operations.{{op}}.messages`

[WiZeYAR]

According to spec, an operation can send/receive a subset of messages that are defined in the channel.

Proposed changes:

1. A compiler must check, if operation.{{op}}.messages or operation.{{op}}.reply.messages exists
2. If they do not exist, the compilation process goes as it did before
3. If they exist, compiler must assert that the messages are indeed a subset of the corresponding channels' messages
4. Generated producers must only take this subset of messages as argument. Any other message type is prohibited.
5. Receiving side must reject the message, if it violates channel message constraints, but nack all messages that do not violate channel constraints, but violate operation ones.
6. If multiple operations consume from the same channel, all operations must confirm that they do not support this message before the nack process occurs.