[pulsarctl] [schemas] `Extract ` command is not supported

[wolfstudy]

In CmdSchemas.java, code logic as follows:

File file  = new File(jarFilePath);
            ClassLoader cl = new URLClassLoader(new URL[]{ file.toURI().toURL() });
            Class cls = cl.loadClass(className);

            PostSchemaPayload input = new PostSchemaPayload();
            SchemaDefinition<Object> schemaDefinition =
                    SchemaDefinition.builder()
                                    .withPojo(cls)
                                    .withAlwaysAllowNull(alwaysAllowNull)
                                    .build();

but in go language, no ClassLoader and pojo, so we can't use go to parse the jar generated in java.

[wolfstudy]

If there are any good ideas or implementations, please let me know.