Adds internal event for when a package is installed which gives access to the InstalledPackage instance which contains a PackageInstance reference that contains all of the files installed in the package
Fixes: U4-5820 List View showing content of complete site after deleting last page of data
Merge branch '7.1.9' into 7.2.0

Conflicts:
	src/Umbraco.Core/Persistence/Repositories/ContentRepository.cs
Fix merge issue