wil::reg::set_value doesn't work with std::wstring values

[Brainy0207]

When you try to call wil::reg::set_value with an std::wstring argument you get a compiler error.

e.g.:

std::wstring my_value = L"Hello";
wil::reg::set_value(HKEY_CURRENT_USER, L"Software\\MyApp", L"MyValue", my_value);

results in:

static_assert failed: 'Unsupported type for set_value_type'

The issue seems to be that reg_view_t::set_value deduces the argument type as const R& value, which will always be the non-const version:

wil/include/wil/registry_helpers.h

Lines 1182 to 1187 in 3ecba60

	template <typename R>
	typename err_policy::result set_value(
	_In_opt_ PCWSTR subkey, _In_opt_ PCWSTR value_name, const R& value, DWORD type = reg_value_type_info::set_value_type<R>()) const
	{
	return set_value_with_type(subkey, value_name, value, type);
	}

It then passes R to reg_value_type_info::set_value_type<R>, but this expects the const version:

wil/include/wil/registry_helpers.h

Lines 1008 to 1012 in 3ecba60

	template <>
	constexpr DWORD set_value_type<const ::std::wstring>() WI_NOEXCEPT
	{
	return REG_SZ;
	}

This probably means that all other smart string variants listed there are also affected.

I think the best approach to fix this would be to switch all the affected set_value_type specializations to non-const.