Roaming profile serialization behaviour has changed in roslyn

[Therzok]

Roslyn PR: dotnet/roslyn#26165

What changed:

• TryPersist uses the first RoamingProfileStorageLocation it can find
• TryFetch probes all the RoamingProfileStorageLocation's it can find

Solution:

• Harden OptionExtensions.GetPropertyName to handle these kind of scenarios.

• Write unit tests for the changes

VS bug #638653

[Therzok]

Setting to high priority as it can cause user settings to be reset without them knowing.

[xamarin-release-manager]

[sync] [VS-15] Comment by xamarinc

Fixed in version 8.6.0.802 (master)

Author: therzok
Commit: b68f95a (xamarin/monodevelop)