[Parser][Printer] Relax types should be namespaced

[altanh]

Currently Relax types in the script format are not namespaced, e.g. x: Tensor[...]. Ideally these should be namespaced like x: relax.Tensor[...] (with the same support for using qualified import, R.Tensor[...]).

This is currently blocked by a synr limitation which requires a breaking change: https://github.com/octoml/synr/issues/16