BuiltProjectOutputGroup target is missing dependency on target that sets AppConfig property

[tmat]

As a result BuiltProjectOutputGroup may not include the generated .config file, depending on the order in which targets are executed.

BuiltProjectOutputGroup target includes the .config file by reading AppConfig property:

<_BuiltProjectOutputGroupOutputIntermediate Include="$(AppConfig)" Condition="'$(AddAppConfigToBuildOutputs)'=='true'">

this property is set in GenerateBindingRedirectsUpdateAppConfig but BuiltProjectOutputGroup does not depend on this target.

[rainersigwald]

Notes:

$(AppConfig) can also be defined in PrepareForBuild

https://github.com/microsoft/msbuild/blob/9eb5d09e6cd262375e37a15a779d56ab274167c8/src/Tasks/Microsoft.Common.CurrentVersion.targets#L1119-L1122

But that looks only at @(None)/@(Content). The missing case is when there's no checked-in app.config file, but ResolveAssemblyReferences/GenerateBindingRedirects creates one.

There's a potential compat/perf problem with the straightforward fix: pulling RAR (and ResolveProjectReferences) into this target which was previously super fast could be bad. This needs to be thought through--can we just do it? Does it need conditions? Entirely opt-in, or not during design time, or ???