[infra] Add PR title checker (#1856)

Author: dcharkes

.github/pr-title-checker-config.json

@@ -0,0 +1,25 @@
+{
+    "CHECKS": {
+        "prefixes": [
+            "[ffi] ",
+            "[ffigen] ",
+            "[infra] ",
+            "[jni] ",
+            "[jnigen] ",
+            "[native_assets_builder] ",
+            "[native_assets_cli] ",
+            "[native_toolchain_c] ",
+            "[objective_c] ",
+            "[swift2objc] ",
+            "[swiftgen] "
+        ],
+        "ignoreLabels": [
+            "skip-pr-title-check"
+        ]
+    },
+    "MESSAGES": {
+        "success": "All OK",
+        "failure": "The PR title has to contain a package name like \"[ffigen]\", or \"[infra]\".",
+        "notice": ""
+    }
+}

.github/workflows/pr-title-checker.yaml

@@ -0,0 +1,25 @@
+name: "PR Title Checker"
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - reopened
+      - synchronize
+  pull_request_target:
+    types:
+      - opened
+      - edited
+      - reopened
+      - synchronize
+      - labeled
+      - unlabeled
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: thehanimo/pr-title-checker@7fbfe05602bdd86f926d3fb3bccb6f3aed43bc70
+        with:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          pass_on_octokit_error: false