Add auth support (#21)

* Updates

* Update

* Update

* Update

* Update

* Yarn sometimes prefers npmrc, so use same token

* Description

* Update readme

* Feedback

* Add type

* new toolkit and scoped registries

* npmrc in RUNNER_TEMP

* Dont always auth

* Try exporting blank token

* Get auth working for now pending runner changes

* Fix string interpolation for auth token.

* Don't export both userconfigs

* Update authutil.js

* Add single quotes for authString

* Fix the registry string.

* Use userconfig and append trailing slash

* Keep in root of repo

* Try just adding auth token

* Remove auth token

* Try changes again

* Add tests

* Npm and GPR samples

* Add types

node_modules/@octokit/rest/plugins/authentication/validate.js

@@ -0,0 +1,21 @@
+module.exports = validateAuth
+
+function validateAuth (auth) {
+  if (typeof auth === 'string') {
+    return
+  }
+
+  if (typeof auth === 'function') {
+    return
+  }
+
+  if (auth.username && auth.password) {
+    return
+  }
+
+  if (auth.clientId && auth.clientSecret) {
+    return
+  }
+
+  throw new Error(`Invalid "auth" option: ${JSON.stringify(auth)}`)
+}