ci: Add wasm sdk installation script.

Author: scottmarchant

scripts/install_wasm_sdk.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+##===----------------------------------------------------------------------===//
+##
+## This source file is part of the Swift.org open source project
+##
+## Copyright (c) 2025 Apple Inc. and the Swift.org project authors
+## Licensed under Apache License v2.0
+##
+## See LICENSE.txt for license information
+## See CONTRIBUTORS.txt for the list of Swift.org project authors
+##
+## SPDX-License-Identifier: Apache-2.0
+##
+##===----------------------------------------------------------------------===//
+
+# TODO: Remove this file once there is a valid reference available in github from
+# this PR: https://github.com/apple/swift-nio/pull/3159
+
+set -euo pipefail
+
+version="$(swiftc --version | head -n1)"
+tag="$(curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/tag-by-version.json" | jq -e -r --arg v "$version" '.[$v] | .[-1]')"
+curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/builds/$tag.json" | jq -r '.["swift-sdks"]["wasm32-unknown-wasi"] | "swift sdk install \"\(.url)\" --checksum \"\(.checksum)\""' | sh -x