Support binding/unbinding between subject and schema

At present, the request path of the REST interface for registering schema will assign a subject, so the schema is naturally bound to this subject after schema registration.
The following two things are expected to be realized:
1、support the unbinding of the schema with the subject, and the binding with a new subject.
2、It is allowed to bind a schema to multiple subjects, that is, multiple subjects share the same schema, and the binding version of each subject can be different.

The expected relationship will be like this.