New Dispatch Callback for Item ItemInstalled

[yanniboi]

I am following the prompt in the screenshot below.

If you want to access a specific callback then please create an issue on github and I'll add it!

Is your feature request related to a problem? Please describe.

I would like my game to be able to respond to new UGC downloaded by steam. In the game, I can create a UI to browse workshop content and subscribe to it actively and that works fine, however steam also supports a user browsing the workshop outside of the game and subscribing to it in that manner. This will then cause the steam client to download that content when the user next logs in/launches the game and I would like to be able to subscribe to an event that notifies me that something has been downloaded in the background and I should update the game accordingly.

Describe the solution you'd like

Steamworks.SteamUGC.InstallEvents() already has a public static event for DownloadItemResult which it uses internally in Steamworks.SteamUGC.DownloadAsync. If a similar static event was available for ItemInstalled, then I could subscribe to that and do what I need to be done.

Describe alternatives you've considered

I could use the existing Dispatch.OnDebugCallback which triggers for all events, but this would severely slow down the game.