Track missing or removed dependencies for MCU kit

Once the kit(s) for MCU support have been created with the valid paths, it can happen that one or more dependencies disappear.  E.g. if the user removes the program manually.

Since these are used to build the package, the cmake process is going to fail and an error message is going to be shown.  From this, the user could troubleshoot the issue.

However, since the version of the dependencies is going to be checked at some point, it could be useful to have a check on the existing kits when starting Qt Creator to check if the dependencies are still there.