[Development] Switching Qt default builds to C++20 where supported

[Tor Arne Vestbø]

> On Nov 27, 2024, at 01:22, Thiago Macieira <thiago.macieira at intel.com> wrote:
> 
> On Tuesday 26 November 2024 08:58:38 Pacific Standard Time Thiago Macieira 
> wrote:
>> That being the case, I'm just not going to do anything. Not my problem any
>> more to move us forward. That also means I will not be doing the work to
>> test our headers in C++23 mode either - that's SEP again.
> 
> Someone who cares about Windows/MSVC may want to take the mantle here, because 
> cpp-winrt will be disabled for C++17.

Please elaborate. Disabled by who, in what configuration, and why? 

Tor Arne