"messageId" must be unique across all the messages.

### Describe the bug
One message cannot be reused in publish and subscribe in the same channel, if a messageId is defined on the message

### To Reproduce
Steps to reproduce the behavior:

0. Assume someMessage has messageId defined.
1. Create a document with a channel like so:
```
channels:
someChannel:
publish:
message:
$ref: "#/components/messages/someMessage"
subscribe:
message:
$ref: "#/components/messages/someMessage"
bindings:
eventstore:
# This is not autogenerated to go code unfortunately
streamName: "someStream"
```
2. Try to `asyncapi generate models golang`
3. See error `error asyncapi2-message-messageId-uniqueness "messageId" must be unique across all the messages.`

### Expected behavior
This should be possible. My usecase is that i want the same service to publish and subscribe to the same eventstore channel, that is used to persist data

Reproduce the issue with `asyncapi generate models golang` using the channel and shared `components/messages/someMessage` reference described here. Start at the `asyncapi2-message-messageId-uniqueness` validation path; done means the same message can be referenced by both publish and subscribe without this error.

Written by the indexing model from the issue text.