Add WinINet impl.

[forderud]

Task: Add WinINet impl. to investigate client-cert support.

Doc:

• https://learn.microsoft.com/en-us/windows/win32/wininet/about-wininet
• https://stackoverflow.com/questions/55297953/client-authentication-certificat-private-key-using-wininet

[forderud]

Done in 9d26492de84d94554d00f0191fe69f015de3d2a8