Update Ngen Priorities for VS

[AlexDelepine]

Adjusting the ngen priorities of a few VS assemblies.

The following assemblies are going from priority 3 to priority 1:
Microsoft.CodeAnalysis.CSharp.Features.dll
Microsoft.CodeAnalysis.CSharp.Workspaces.dll
Microsoft.CodeAnalysis.EditorFeatures.dll
Microsoft.CodeAnalysis.LanguageServer.Protocol.dll

This one from priority 3 to priority 2:
Microsoft.CodeAnalysis.Remote.Workspaces.dll

And this one from priority 1 to 3:
Microsoft.CodeAnalysis.Remote.ServiceHub.dll

We are experimenting with a mechanism to asynchronously generate important NGEN images immediately after VS setup in 17.14, and to do this are adjusting NGEN priorities of assemblies, so that the most important ones, based on JIT time, usage and user observable scenarios, are generated first. These changes are as a result of that analysis. If you have any questions on this, feel free to reach out to me or the VS Perf and Rel team.

[jasonmalinowski]

This one from priority 3 to priority 2:
Microsoft.CodeAnalysis.Remote.Workspaces.dll

And this one from priority 1 to 3:
Microsoft.CodeAnalysis.Remote.ServiceHub.dll

I'd imagine those would both load about the same time so I'm surprised we'd have different priorities for them.

[AlexDelepine]

@jasonmalinowski the new priorities were assigned based on JIT time of a few different scenarios that we tested, so even if some assemblies may load at the same time, the amount of time that is spent jitting is different so the priorities differ based on that.

[RikkiGibson]

Kicking off a validation insertion. We should have results by EOD or tomorrow AM. https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=11294552&view=results

edit: the first attempt seems to have failed in some unrecoverable way. replaced with a link to second attempt.

[JoeRobich]

New validation insertion run: https://dev.azure.com/devdiv/DevDiv/_build/results?buildId=11318955&view=results