Tooling to support add-ons in Boot2Qt

Enable developers (us and 3rd party vendors) to provide additional components on top of Boot2Qt images, and users to add those components to their images and toolchains.

The installable add-on packages will be collections of packages (IPK for example) that can be installed into the device using the already provided package manager (opkg), the same packages are also needed in the cross-compilation toolchain (sysroot) to allow user to develop application with those components.

Tooling is needed for the developer to allow packaging of all the needed components into the single archive that can then be delivered to the end users.

Tooling is needed for end users to easily install the add-ons into their images without needing to know the actual technical details behind the process. The tooling must be cross-platform and support updating the device and the cross-compilation toolchains.