Investigate propagating values of per-abi target properties like QT_ANDROID_EXTRA_LIBS to the main project's deployment json file

Currently if a user project sets per-abi values to target properties like QT_ANDROID_EXTRA_LIBS, they are not propagated back to the main project when doing a multi-abi Android build.

Consider automatic collection of this information by having each per-abi sub-project generate a new cmake or json file with relevant values, which can then be fed to the main project androiddeployqt call.

Either androiddeployqt will have to learn to read multiple json files, or we need an additional build step that would merge all the information into a new json file to feed to androiddeployqt.

The current workaround is to specify the complete list of all libraries or plugins that need to be deployed directly in the main project, without relying on information like the current active architecture that the project is being built for.