Add support for powershell scripts license header checking

Author: FranzBusch

.github/workflows/scripts/check-license-header.sh

@@ -57,6 +57,7 @@ while IFS= read -r file_path; do
     h) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     c) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     sh) expected_file_header=$(cat <(echo '#!/bin/bash') <(sed -e 's|@@|##|g' <<<"${expected_file_header_template}")) ;;
+    ps1) expected_file_header=$(sed -e 's|@@|##|g' <<<"${expected_file_header_template}") ;;
     kts) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     gradle) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;
     groovy) expected_file_header=$(sed -e 's|@@|//|g' <<<"${expected_file_header_template}") ;;

tests/test.ps1

@@ -0,0 +1,11 @@
+## ===----------------------------------------------------------------------===##
+##
+## This source file is part of the Swift.org open source project
+##
+## Copyright (c) 2024 Apple Inc. and the Swift project authors
+## Licensed under Apache License v2.0 with Runtime Library Exception
+##
+## See https://swift.org/LICENSE.txt for license information
+## See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+##
+## ===----------------------------------------------------------------------===##