Implement IProgress<int> in ApiWebAppDeployer

[KircMax]

As a GUI creator I would like to be able to

• [ ] know how many items the ApiWebAppDeployer will have to take care of (appExceptBrowsed.Count)
• [ ] show the progress of the ApiWebAppDeployer deployment => after each DeployResourceAsync(webApp, r); 1 more is done
• [ ] Use a method GetDifferenceAsync(ApiWebAppData webApp) that will determine the appExceptBrowsed.Count => will return all items of the webApp in case it is not yet present on the plc

Consider also implementing an Event OnDeployFinished or something alike (then the deploy step itself might also just be performed "fully" in the background and not awaited in the GUI)

[KircMax]

same would be applicable in the ApiDirectoryHandler