Check namespaceId is exist when some api need namespace to handle

[horizonzy]

Describe the bug
Now I register a instance with the not exist namespaceId. In server, com.alibaba.nacos.naming.core.ServiceManager will create a new namesapce, and put service in it.
For this situation, we should check the namespaceId is exist. If the situation is not exist, throw an exception.

[KomachiSion]

If need to check whether namespace is exist, it will depend persistency module first.

we may need to discuss and extract the persistency module first

[horizonzy]

Maybe we can add a filter in console module to fix it

[KomachiSion]

And need to cache namespace in memory, and need to maintain the cache.

[CaiJiHuzhuo]

I noticed in the nacos documentation that the namespace module will be moved to the public module. which module? common?

[horizonzy]

I think move it to core module will be better, like authFilter.

[realJackSun]

Add a NamespaceFilter like this?

public class NamespaceFilter implements Filter {
    Set<String> existingNamespaces;
    ...
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
        String namespace = request.getNamespace();
        if (!existingNamespaces.contains(namespace)) {
             existingNamespaces.replace(namespace, "public");
       }
   }
}