Slightly improve I/O code quality

[kingcrimsontianyu]

Description

This PR makes small improvements for the I/O code. Specifically,

• Place type constraint on a template class to allow only for rvalue argument. In addition, replace std::move with std::forward to make the code more apparently consistent with the convention, i.e. use std::move() on the rvalue references, and std::forward on the forwarding references (Effective modern C++ item 25).
• Leave comments regarding an existing cuFile driver close issue.
• Minor typo fix (struct → class).

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.