Download blobs from MSRC storage & Add CredProvider to Dockerfiles (#4753)

* Download core-setup files from MSRC storage

Add support for downloading core-setup files from an authenticated endpoint

* Update GenerateLayout.targets

* Adding changes to pass SAS token around

* Add credential provider to Dockerfile's

* Update after PR feedback

* Add comments about approach

* Copy NuGet config variables

eng/dockerrun.sh

@@ -142,7 +142,13 @@ docker run $INTERACTIVE -t --rm --sig-proxy=true \
     -e BUILD_SOURCEBRANCH \
     -e BUILD_BUILDNUMBER \
     -e BUILD_SOURCEVERSION \
+    -e SYSTEM_TEAMPROJECT \
+    -e DOTNECLIMSRC_READ_SAS_TOKEN \
     -e AGENT_JOBNAME \
     -e AGENT_OS \
+    -e VSS_NUGET_URI_PREFIXES \
+    -e VSS_NUGET_ACCESSTOKEN \
+    -e DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER=0 \
+    -e NUGET_CREDENTIALPROVIDER_SESSIONTOKENCACHE_ENABLED=true \
     $DOTNET_BUILD_CONTAINER_TAG \
     $BUILD_COMMAND "$@"