Add deprecation warnings

This merely ports the changes already made to the other analyzer binaries:
https://dart-review.googlesource.com/c/sdk/+/219702

Change-Id: If848b164eff7d9bf166734aaad437749e44b04a4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229143
Reviewed-by: William Hesse <whesse@google.com>
Commit-Queue: Michael Thomsen <mit@google.com>

Author: mit-mit

sdk/bin/dartanalyzer_sdk

@@ -6,6 +6,8 @@
 # Run dartanalyzer.dart on the Dart VM. This script assumes the Dart SDK's
 # directory structure.
 
+echo "Warning: 'dartanalyzer' is deprecated. Please use 'dart analyze'." 1>&2
+
 function follow_links() {
   file="$1"
   while [ -h "$file" ]; do

sdk/bin/dartanalyzer_sdk.bat

@@ -3,6 +3,8 @@ REM Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 REM for details. All rights reserved. Use of this source code is governed by a
 REM BSD-style license that can be found in the LICENSE file.
 
+echo Warning: 'dartanalyzer' is deprecated. Please use 'dart analyze'. 1>&2
+
 setlocal
 rem Handle the case where dart-sdk/bin has been symlinked to.
 set DIR_NAME_WITH_SLASH=%~dp0