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

src/index.js

@@ -0,0 +1,10 @@
+const core = require('@actions/core');
+const { exportSecrets } = require('./action');
+
+(async () => {
+    try {
+        await core.group('Get Vault Secrets', exportSecrets);
+    } catch (error) {
+        core.setFailed(error.message);
+    }
+})();