Qt6 Conan.io Poc: Packaging requirements

Requirements from packaging/releasing perspective:

1. Package pre-built binaries
   1. CI system produces binaries per Qt project (qtbase, qtsvg, ...)
      1. All the dependencies (Qt binaries) are available for packaging
   2. Possibility to further create packages per Qt module (not per .git repository)
      1. QtCore, QtGui, QtNetwork...
2. Define dependencies between packages
   1. Per package name (e.g. qtsvg -> qtbase)
   2. Per package version (e.g. qtsvg 1.2.3 -> qtbase 1.2.3)
3. Multiple build configurations (per-built binaries) per project/module
   1. RHEL_X_X, MSVC_XXXX, macOS_X_X, Android_X_X, ...
4. Custom meta-data per package
   1. Possibility to annotate packages with free form text/meta-data. This is needed by CLI/Installer UI to further categorize available packages / improved user experience
      1. title, description, build_date, sha1, alpha1/rc2/final, ... 
      2. product name / part of product
      3. platform name
      4. supported time stamp
      5. binary package host_os, host_os_version, host_arch, host_compiler, target_os, target_XYZ, features, ...
5. Sign packages
6. SDK creation
   1. Others should be able to create installer with the same system
7. Easy conversion from open-source to commercial installation
8. Cleaning old snapshots/revisions from online repositories

Good to have:

1. Concept of "latest" package revision
   1. Releasing produces regular nightly snapshots, the version number or package revision increases every iteration
   2. Users should be able to install the "latest" version without specifying the exact revision number and pull updates similarly
2. "flag" the selected packages as final
   1. When making rc1, rc2, ... the latest rc version will be selected as the final version. It should be enough to "flag" / edit the latest version as final without re-packaging the whole product