Qt6: add check for modules getting found

[SvenRoederer]

Summary

Changes to recipe: qt/6.x

Motivation

This adds a test for the issue seen in #23660 "Qt-modules not found".

Details

Even we are using Windows, but not Android as the mentioned issue, we had seen the same problem with QML-modules. WE added a test-application, which I'd like to share.
The PR involves 2 changes:

• extending the current general test-code to ensure the Qt-plugins are found
• adding a 2nd optional test to look for QML-modules, when feature "qtdeclarative" is enabled

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan

[CLAassistant]

All committers have signed the CLA.

[conan-center-bot]

Conan v1 pipeline ❌

Warning

Conan Center will stop receiving updates for Conan 1.x packages soon - please see announcement.

Failure in build 10 (1096e17f2f5313ad60962e4016a44c87c1edbbde):

• qt/5.15.14:
  CI failed to create some packages (All logs)

  Logs for packageID 2f4a521a888609c32ffa6a7e61a56c18d563ee4e:

  [settings]
  arch=x86_64
  build_type=Release
  compiler=gcc
  compiler.libcxx=libstdc++11
  compiler.version=9
  os=Linux
  [options]
  qt:shared=False
  

  [...]
      CMAKE_INSTALL_SBINDIR
      CONAN_COMPILER_VERSION
      CONAN_EXPORTED
      CONAN_IN_LOCAL_CACHE
  
  
  "List of Plugin Modules: "
  "bearer"
  "generic"
  "imageformats"
  "platforminputcontexts"
  "platforms"
  "sqldrivers"
  "xcbglintegrations"
  Resource content: "Hello World From Resource\n"
  2
  inside f
  "Hello World!"
  WARN: **************************************************
  WARN: *** Conan 1 is legacy and on a deprecation path **
  WARN: *********** Please upgrade to Conan 2 ************
  WARN: **************************************************
  WARN: openssl/3.3.2: requirement zlib/[>=1.2.11 <2] overridden by qt/5.15.14 to zlib/1.3.1 
  WARN: pcre2/10.42: requirement zlib/[>=1.2.11 <2] overridden by qt/5.15.14 to zlib/1.3.1 
  WARN: freetype/2.13.2: requirement libpng/[>=1.6 <2] overridden by qt/5.15.14 to libpng/1.6.44 
  WARN: freetype/2.13.2: requirement zlib/[>=1.2.10 <2] overridden by qt/5.15.14 to zlib/1.3.1 
  WARN: libpng/1.6.44: requirement zlib/[>=1.2.11 <2] overridden by freetype/2.13.2 to zlib/1.3.1 
  WARN: libmysqlclient/8.1.0: requirement openssl/[>=1.1 <4] overridden by qt/5.15.14 to openssl/3.3.2 
  WARN: libmysqlclient/8.1.0: requirement zlib/[>=1.2.11 <2] overridden by qt/5.15.14 to zlib/1.3.1 
  WARN: libxml2/2.13.4: requirement zlib/[>=1.2.11 <2] overridden by xkbcommon/1.5.0 to zlib/1.3.1 
  WARN: wayland/1.22.0: requirement libxml2/[>=2.12.5 <3] overridden by xkbcommon/1.5.0 to libxml2/2.13.4 
  qt/5.15.14 (test package): WARN: 
       ************************************************
       The 'cmake_find_package_multi' generator is deprecated.
       Please update your code and remove it.
       *************************************************
  
  qt/5.15.14 (test package): WARN: 
       ************************************************
       The 'qmake' generator is deprecated.
       Please update your code and remove it.
       *************************************************
  
  qt/5.15.14 (test package): WARN: 
       ************************************************
       The 'cmake' generator is deprecated.
       Please update your code and remove it.
       *************************************************
  
  qt/5.15.14 (test package): WARN: **** The 'from conans import CMake' helper is deprecated. Please update your code and remove it. ****
  

• qt/6.7.3:
  Didn't run or was cancelled before finishing

• qt/6.6.3:
  Didn't run or was cancelled before finishing

• qt/6.5.3:
  Didn't run or was cancelled before finishing

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Conan v2 pipeline ✔️

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All green in build 10 (1096e17f2f5313ad60962e4016a44c87c1edbbde):

• qt/5.15.14:
  Built 8 packages out of 10 (All logs)

• qt/6.7.3:
  Built 4 packages out of 10 (All logs)

• qt/6.6.3:
  Built 4 packages out of 10 (All logs)

• qt/6.5.3:
  Built 6 packages out of 10 (All logs)

[SvenRoederer]

Not sure, why the Conan v1 pipeline fails to build for qt/5.15.14, but as it fails during building the package, it's not related to the changes here.