Previously, local tvf can only query data on one BE node.
But if the storage is shared(eg, NAS), it can be executed on multi nodes.
This PR mainly changes:
1. Add a new property `"shared_stoage" = "false/true"`
Default is false, if set to true, "backend_id" is optional. If "backend_id" is set,
it still be executed on that BE, if not set, "shared_stoage" must be "true"
and it will be executed on multi nodes.
Doc: https://github.com/apache/doris-website/pull/494