Raise an error if ther are upstream changes before running TAF metadata, targets commands

[n-dusan]

We shouldn't update metadata if the repository isn't up to date.

[renatav]

Do we want to automatically update or raise an error if the repository is not up to date?

[renatav]

My final suggestion is to simply raise an error if there are upstream changes, instead of automatically running the updater. The user might want to take a look at those changes before updating anything. I'll integrate this into one of reworks