Avoid relying on `typing.TYPE_CHECKING` to the maximum possible extent

During investigation of #454 and related doc rendering issues, it has come to my attention that the type checking detection logic does not work well with Sphinx (ex: https://github.com/sphinx-doc/sphinx/issues/13137, https://github.com/sphinx-doc/sphinx/issues/11225).

Independently, Ralf has pointed out that it makes code debugging harder (https://github.com/NVIDIA/cuda-python/pull/463#discussion_r1967029167).

The idea of having a if TYPE_CHECKING: check is to avoid unnecessary imports or circular imports. If such issues do not exist, we should avoid using it.

まず、#454 に関係する TYPE_CHECKING の使用箇所と、関連する Sphinx の issue を確認し、不要な import や循環 import を防いでいる guard を特定します。これらの import が Sphinx のレンダリングとデバッグにどのような影響を与えるかを確認します。不要な TYPE_CHECKING guard が削除され、import の安全性に必要な guard が残っていれば完了です。