chore: Add IDETemplateMacros.plist for file header generation with spm [skip ci] (#1794)

Author: atierian

.swiftpm/xcode/xcshareddata/IDETemplateMacros.plist

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+  <key>FILEHEADER</key>
+  <string>
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//</string>
+</dict>
+</plist>