add qtgraphs cmake target generation

[StofflR]

Summary

Changes to recipe: qt/6.8.x+

Motivation

Adds missing Cmake Targets for QtGraphs submodule.

fixes #29212

Details

Added _create_module call for QtGraphs in package_info.

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• Checked that this PR is not a duplicate: list of PRs by recipe
• If this is a bug fix, please link related issue or provide bug details
• Tested locally with at least one configuration using a recent version of Conan

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[jcar87]

Thanks @StofflR for your contribution.
The PR looks good, but I'm unable to use it in a toy example for Qt graphs:
I'm trying with https://doc.qt.io/qt-6/qtgraphs-2d-quickwidgetgraphs-example.html
(https://code.qt.io/cgit/qt/qtgraphs.git/tree/examples/graphs/2d/quickwidgetgraphs?h=6.10)

IN particular linker errors - I can work around some of the CMake stuff, but I cant find any combination of libraries to get this to link on macOS using the static variant.

Any pointers appreciated - the Qt recipe is quite challenging and we are now attempting to verify the fixes locally, thanks!

[StofflR]

Hi @jcar87 thanks for reviewing.

Tbh I've never attempted a static build of an Qt application, as far as I'm concerned that'd require changing the provided example. If you have some specific questions about that I can try to help, but not sure if I can.

I've used the following settings for building it (https://doc.qt.io/qt-6/qtgraphs-2d-quickwidgetgraphs-example.html) using shared libraries.

conanfile.txt:

[requires]
qt/6.10.1

[generators]
CMakeDeps
CMakeToolchain

[options]
qt/*:graphs=True
qt/*:qtquick3d=True
qt/*:shared=True

And then simply running: conan install . -of=build , cmake --preset conan-release and cmake --build --preset conan-release. Seems to work fine on linux.