Use .license_header_template

Author: MaxDesiatov

.github/workflows/pull_request.yml

@@ -15,4 +15,3 @@ jobs:
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
     with:
       api_breakage_check_enabled: false
-      license_header_check_project_name: "Swift"

.license_header_template

@@ -0,0 +1,12 @@
+@@===----------------------------------------------------------------------===@@
+@@
+@@ This source file is part of the Swift open source project
+@@
+@@ Copyright (c) YEARS 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
+@@
+@@===----------------------------------------------------------------------===@@
+