Update to Qt6 and add PowerShell update script

[jeremyong]

This PR does the following changes:

1. Synchronize code with the latest Qt-Creator update (pulled as of 2023-05-06)
2. Massage the patch file to account for upstream changes
3. Change the test implementation to account for the fact that FakeVimHandler signals are now callbacks
4. Add a PowerShell script (useful for Windows users, but also PowerShell users on other platforms)
5. Remove the C++17 cmake module in favor of the more modern target_compile_features built-in function provided by CMake. I opted to bump the version to C++20, given that most modern Qt projects will be using this.

To test changes, I ran the entire test suite and observed no regressions:

I also compiled and ran the example to verify things worked as expected.

[hluk]

Thanks a lot!

I'm hesitant to merge this because some project still use Qt 5. For example CopyQ clipboard manager supports Qt 6 but also needs to support Qt 5 for older Linux distributions and due to some dependencies not being fully compatible with Qt 6 yet (like KDE Frameworks - but maybe it is a distro packaging problem).

[jeremyong]

Yep completely understood. Would it make sense for us to have a qt6 branch?

[hluk]

Yep completely understood. Would it make sense for us to have a qt6 branch?

That sounds good. Maybe even a duplicate CI workflow (.github/workflows/cmake.yml) for the branch and Qt 6 but that will require to figure out the versions of packages to install with apt-get

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[wineee]

It's 2026 now, we can consider prioritizing Qt6.

[hluk]

It's 2026 now, we can consider prioritizing Qt6.

Yeah, it is safe to drop Qt 5 support now - AFAIK, it is no longer maintained.