Remove the NuGetOperationType from NuGet.PackageManagement, use NuGetProjectActionType instead

[nkolev92]

While working conditional PR updating, I noticed myself doing a lot of duplicated work. See more details for motivation: https://github.com/NuGet/NuGet.Client/compare/dev-nkolev92-conditionalPackageReferenceUpdating?expand=1

For example, I had to do lots of conversions with NuGetProjectActionType and NuGetOperationType.
This is redundant, and makes our code more complicated.

I looked at the references and the only place where the NuGetOperationType is explicitly used is as an API is ActionTelemetryEvent, which is not used a lot.

Consolidating these types simplifies the NuGet code and makes future updates simpler.

[ghost]

@nkolev92 Issue is missing Type label, remember to add a Type label

[nkolev92]

Fixed in NuGet/NuGet.Client#5394

[ghost]

@nkolev92 Issue is missing Type label, remember to add a Type label