<locale>: std::ctype<char>::blank return true for all space-characters

Describe the bug
blank returns true for '\r', '\n' ... it just works as an alias for std::ctype::space

From https://en.cppreference.com/w/cpp/string/byte/isblank

In the default C locale, only space (0x20) and horizontal tab (0x09) are classified as blank characters.

Command-line test case

C:\Temp>type main.cpp
#include <iostream> 
#include <locale> 
#include <cctype>

using namespace std;

int main()
{ 
	cout << isblank('\n') << '\n';
	cout << use_facet<ctype<char>>(locale("C")).is(ctype<char>::blank,
		static_cast<unsigned char>('\n')) << '\n';
	cout << use_facet<ctype<char>>(locale::classic()).is(ctype<char>::blank,
		static_cast<unsigned char>('\n')) << '\n';
}

C:\Temp>cl /EHsc /W4 /WX main.cpp
cl /EHsc /W4 /WX main.cpp
Оптимизирующий компилятор Microsoft (R) C/C++ версии 19.27.29109 для x64
(C) Корпорация Майкрософт (Microsoft Corporation).  Все права защищены.

main.cpp
Microsoft (R) Incremental Linker Version 14.27.29109.0
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:main.exe
main.obj

C:\Temp>main.exe
0
1
1

Expected behavior
Should return 0 0 0

STL version
Microsoft Visual Studio Community 2019 Preview Version 16.7.0 Preview 6.0
Additional context
VSO-429255 / AB#429255 | DevCom-215436 DevCom-246252 DevCom-51443

Start by reproducing the command-line test case and compare std::isblank with use_facet<ctype> for locale("C") and locale::classic(). Trace the ctype::blank classification entry point. Done means the facet calls classify '\n' consistently with std::isblank and the regression is covered by the project’s tests.