ci: Add pull request CI workflows.

Author: scottmarchant

.github/workflows/pull_request.yml

@@ -0,0 +1,22 @@
+name: Pull request
+
+on:
+  pull_request:
+    types: [opened, reopened, synchronize]
+
+jobs:
+  soundness:
+    name: Soundness
+    uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
+    with:
+      license_header_check_project_name: "Swift.org"
+
+  tests:
+    name: tests
+    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
+
+  wasm-sdk:
+    name: WebAssembly SDK
+    # TODO: Switch to this line after https://github.com/apple/swift-nio/pull/3159/ is merged
+    # uses: apple/swift-nio/.github/workflows/wasm_sdk.yml@main
+    uses: kateinoigakukun/swift-nio/.github/workflows/wasm_sdk.yml@katei/add-wasm-ci