Refactor of how vsgMacros.cmake and vsg_glslangConfig.cmake are installed/used

[Robert Osfield]

Hi All,

I have just merged a series of PR's from Ralf Habacker that shares vsgMacros.cmake with dependent projects by installing vsgMacros.cmake in lib/cmake/vsg alongside the standard VSG cmake config files.

This means that the local vsgMacros.cmake, that I added a few months back to help the builds that pull in VSG projects using FetchContent and or as git submodule, are no longer required so the dependent projects are all simplified.

Changes to VSG master: https://github.com/vsg-dev/VulkanSceneGraph/pull/563/files

Changes to vsgXchange master: https://github.com/vsg-dev/vsgXchange/pull/127/files

Changes to vsgImGui, vsgQt and vsgExamples are similar to vsgXchange changes.

I took this opportunity to move vsg_glslangConfig.cmake into lib/cmake/vsg directory when installing so there is no longer a dedicated lib/cmake/vsg_glslang directory.  I did this avoid confusion and hopefully catch a few instances where users had problems locating the vsg_glslang support, as it's now all pulled in automatically by the find_packace(vsg) when the VSG is compiled against glslang.

These change look to be building fine but there I can't rule out oddities on some build platforms and applications so testing out in the the community would be very much appreciated.

If the VSG, vsgXchange, vsgImGui, vsgQt, vsgExamples and vsgFramwork master all look to be getting along fine and build for everyone I'll merge these changes with the respective 1.0 branches.

Cheers,

Robert.