Manage platform specific SDK requirements needing by Qt Creator in Qt

Building apps for platforms like Android or WebAssembly require a bunch of dependencies in addition to Qt to be ready for Qt Creator to be able to do any builds. For Android this can be an NDK, SDK platform, build-tools, etc. At the moment Qt Creator keeps a json file to track such dependencies and their versions. For example Qt 5.12 might need an NDK r19 while a Qt 6.2 needs an NDK r22b. The problem with that is that changes in Qt might not necessarily be rejected in Qt Creator, especially when using a new Qt version with an older Qt Creator version.

To fix this, we can track any dependency relations and versioning in Qt itself, and Qt Creator would merely read those. Qt Creator already uses qmake to get some information about Qt:

qmake -query

AFAIK, that gets the data from qt.conf and target_qt.conf files under bin folder of the installed Qt version.

Discussion:

The following points remain open questions for me:

• Would this approach work for various Qt platforms?
• Would qmake -query be the right way going forward, especially since we're using CMake nowadays. 
  • if not, we need a place that works for every build system.

This is a result of some discussions about managing NDKs in Creator, a summery on QTCREATORBUG-26725.