implement `std::ops::Not` for `StdLib`

[mokurin000]

Scenario: I want basically ALL_SAFE feature set, but except PACKAGE,

        Lua::new_with(
            StdLib::ALL_SAFE & StdLib(!StdLib::PACKAGE.0),
            LuaOptions::new(),
        )?

This is not allowed because .0 is private

        Lua::new_with(
            StdLib::ALL_SAFE & !StdLib::PACKAGE,
            LuaOptions::new(),
        )?

This is also not allowed due to Not not implemented by StdLib