[Prev6] Update MicrosoftPrivateIntellisensePackage and XmlDocFileRoot

[carlossanlop]

PR for master: #38109

This PR will update the Intellisense from Preview6 with what was generated from Preview5.

XmlDocFileRoot was defined in two places: packaging.props and docs.targets.
Moved it to a higher level to ensure it's only defined once, in Directory.Build.props. Made sure to define it after NuGetPackageRoot is defined.
Also made sure the folder it reads is net instead of netcoreapp, because the Docs build saves the .NET 5.0 intellisense files in the net folder, and the .NET 3.1 intellisense files in the netcoreapp folder.
Updated the nupkg to consume to the latest available version in the feed 20200602.3, which contains the Preview5 APIs.

Note: The version is not being downgraded from 3.1 to 3.0. The Docs build uploads the nupkg to the feed with that name. We will ask them to rename it to avoid confusion.

[ghost]

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[carlossanlop]

The CI will most likely hit a build failure. Santi and I are investigating it.

Update: Fixed. Moved the XmlDocFileRoot definition to Versions.props.

[safern]

@danmosemsft @mmitche can we take this change for Preview6 still? Currently the intellisense we're shipping are from 3.1.

[mmitche]

@danmosemsft @mmitche can we take this change for Preview6 still? Currently the intellisense we're shipping are from 3.1.

We don't have the runway for 5.0 p6

[safern]

We don't have the runway for 3.1

What do you mean? I meant that the intellisense xml files that we're including in Preview6 and master without this change are using the xml files from 3.1 release, so it would be nice if we could take this change to use the xml files produced from 5.0-Preview6.

[danmoseley]

Can you clarify the impact -- you're saying that currently if I use VS to develop against Preview 6 (and previous 5.0 previews) I will get no intellisense for API that's new in 5.0? Or I just won't get the descriptions?

[mmitche]

We don't have the runway for 3.1

What do you mean? I meant that the intellisense xml files that we're including in Preview6 and master without this change are using the xml files from 3.1 release, so it would be nice if we could take this change to use the xml files produced from 5.0-Preview6.

Sorry I meant p6

[safern]

Or I just won't get the descriptions?

Just the descriptions. This has been this way for all the previous previews, so we could wait for P7.

[carlossanlop]

@safern the build failed here, even though the changes are the same as in master.

@mmitche should we close this PR then?

[mmitche]

@safern the build failed here, even though the changes are the same as in master.

@mmitche should we close this PR then?

Yep