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/index.js

@@ -0,0 +1,21 @@
+module.exports = authenticationPlugin
+
+const beforeRequest = require('./before-request')
+const requestError = require('./request-error')
+const validate = require('./validate')
+
+function authenticationPlugin (octokit, options) {
+  if (!options.auth) {
+    return
+  }
+
+  validate(options.auth)
+
+  const state = {
+    octokit,
+    auth: options.auth
+  }
+
+  octokit.hook.before('request', beforeRequest.bind(null, state))
+  octokit.hook.error('request', requestError.bind(null, state))
+}