Add the "@actions/exit" package

It is useful to have the exit logic separated into its own package

packages/exit/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "baseUrl": "./",
+    "outDir": "./lib",
+    "rootDir": "./src"
+  },
+  "include": [
+    "./src"
+  ]
+}