deps.qt: Add Qt Designer

[derrod]

Description

Build Qt Designer with our Qt deps

Motivation and Context

We should have always have a readily available version of designer people can use without having to suffer through Qt's maintenance tool and download like 3 GB of Qt builds and/or Qt Creator which may or may not be built against an older Qt version.

Additionally this avoids issues where people use "whatever they had insatlled" which may not match the version OBS is using (on macOS/Windows at least) and make changes to the XML format that don't match the shipping version.

Should also help unblock https://github.com/obsproject/obs-studio/pull/10419

How Has This Been Tested?

We'll see if we compile ey?

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[derrod]

For some reason designer components were built, but the binary designer.exe was not created/installed, I guess this will require another dive into Qt Cmake...

[RytoEX]

I did some digging and it looks like -DQT_BUILD_TOOLS_BY_DEFAULT:BOOL=OFF is the culprit here. We can try setting it back to ON just in the qttools configuration.

I filed QTBUG-125067 in case this behavior is not intentional.

[derrod]

Yeah setting that to ON just for qttools works, latest CI artifact has Qt Designer binaries.

[RytoEX]

Just to keep track of it, adding Qt Designer (qttools) adds 3m34s to the download+configure+build+install step on the Windows x64 RelWithDebInfo build and 4m00s for macOS.