Add a license check for each file to CI

.github/check-license-headers.yaml

@@ -0,0 +1,38 @@
+[
+  {
+    "include": [
+      "**/**/*.rs"
+    ],
+    "exclude": [
+      "target/**",
+      "*/LICENSE*",
+      "LICENSE.md",
+      "RELEASE.md",
+      "rpc/**",
+      "README*",
+      "*/README*",
+      "Cargo.toml",
+      "*/Cargo.toml",
+      "libaio/**",
+      "docs/**",
+      "CODEOWNERS"
+    ],
+    "license": "./.github/license-header.txt"
+  },
+  {
+    "include": [
+      "target/**",
+      "*/LICENSE*",
+      "LICENSE.md",
+      "RELEASE.md",
+      "rpc/**",
+      "README*",
+      "*/README*",
+      "Cargo.toml",
+      "*/Cargo.toml",
+      "libaio/**",
+      "docs/**",
+      "CODEOWNERS"
+    ],
+  }
+]

.github/license-header.txt

@@ -0,0 +1,2 @@
+// Copyright (C) %year%, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE.md for licensing terms.

.github/workflows/ci.yaml

@@ -80,6 +80,12 @@ jobs:
       - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
+      - name: Check license headers
+        uses: viperproject/check-license-header@v2
+        with:
+          path: .
+          config: .github/check-license-headers.yaml
+          strict: true
       - name: Restore Check Deps
         id: cache-build-deps-restore
         uses: actions/cache/restore@v3