Run _CheckForInvalidConfigurationAndPlatform in design-time builds

[dsplaisted]

Should fix the VS side of dotnet/sdk#798

The targets which currently get run as part of _CheckForInvalidConfigurationAndPlatform are:

• _CheckForUnsupportedTargetFramework
• CheckForDuplicateItems
• _CheckForInvalidConfigurationAndPlatform
• CheckForImplicitPackageReferenceOverrides

[davkean]

This isn't a complete fix - design-time builds are more than compile. Basically any target can run as a design-time build if there's a rule for it.

[davkean]

I'm not convinced their change to drop this target from being included in InitialTargets was a wise one, I think we've probably just regressed legacy.

[dsplaisted]

Yes, after testing this I'm not sure whether we should try fixing this by changing the design time targets. The targets that are run by the project system when I try it out are:

• CollectResolvedSDKReferencesDesignTime
• CollectPackageReferences
• ResolveComReferencesDesignTime
• ResolveProjectReferencesDesignTime
• ResolveAssemblyReferencesDesignTime
• CollectSDKReferencesDesignTime
• ResolvePackageDependenciesDesignTime
• CompileDesignTime

Rather than make all of these targets depend on _CheckForInvalidConfigurationAndPlatform, a simpler solution is to modify the _CheckForUnsupportedTargetFramework target to run before GetReferenceAssemblyPaths.

[davkean]

I think the better change is to switch it back to being a initial target.

[davkean]

Going to close this PR - ping me if you still think this is the right approach, instead of adding it back to initial targets.

[davkean]

Side note, this still isn't all the design-time targets - any target can be a design-time target when using the MSBuild single file generator.