feat: add generic auth (#39)

* feat: add generic auth

Adds the ability to authenticate against any normal Vault endpoint by added the `authPayload` input.

When an unrecognized method is provided, the action will attempt to hit `v1/auth/<method>/login` with the provided `authPayload and parse out the token in the response

tsconfig.json

@@ -0,0 +1,12 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "target": "es2019",
+        "moduleResolution": "node",
+        "allowJs": true,
+        "noEmit": true
+    },
+    "exclude": [
+        "node_modules"
+    ]
+}