[Feature request]: Report if we're updating or installing

[razzeee]

Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Suggestion

There are some known inconsistencies, which our current approach to figure out if flatpak is doing an install or an update.

As far as I understand, this seems to stem from flatpak doing an install on an already installed app, if it's too old and we can't delta update. See flathub/flathub#177 (comment)

The problem is, we can't separate these in the logs. So adding the metadata to the useragent would allow us to know, if the user updated or installed an app. And thus fix our statistics.

Might be here where we could add it https://github.com/flatpak/flatpak/blob/main/common/flatpak-dir.c#L5393