McuSupport: Re-generate "outdated" kits on start-up

The way, MCU kits get created is frequently changing due to changes in Qt for MCs itself or in Qt Creator. Therefore, previously generated Kits can easily get outdated.

Instead of relying on that the user actively re-generates the MCU kits, we should have a mechanism that at startup checks existing MCU kits, and replaces them with updated ones.

Some inspiration can be taken from IosConfigurations::updateAutomaticKitList(), triggered by KitManager::kitsLoaded

Ideally, the updated kits retain the original kit ID, so taht configured projects remain functional.