Add dedicated scripts for restore

Proposing we add these. It's part of my workflow to do a restore before
opening VS because I always disable package restore inside VS.

Any objections?

Author: rynowak

restore.cmd

@@ -0,0 +1,3 @@
+@echo off
+powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\common\Build.ps1""" -restore %*"
+exit /b %ErrorLevel%

restore.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+source="${BASH_SOURCE[0]}"
+
+# resolve $SOURCE until the file is no longer a symlink
+while [[ -h $source ]]; do
+  scriptroot="$( cd -P "$( dirname "$source" )" && pwd )"
+  source="$(readlink "$source")"
+
+  # if $source was a relative symlink, we need to resolve it relative to the path where the
+  # symlink file was located
+  [[ $source != /* ]] && source="$scriptroot/$source"
+done
+
+scriptroot="$( cd -P "$( dirname "$source" )" && pwd )"
+"$scriptroot/eng/common/build.sh" --restore $@