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

action.yml

@@ -5,6 +5,10 @@ inputs:
   version:
     description: 'Version Spec of the version to use.  Examples: 10.x, 10.15.1, >=10.15.0, lts'
     default: '10.x'
+  registry-url:
+    description: 'Optional registry to set up for auth. Will set the registry in a project level .npmrc and .yarnrc file, and set up auth to read in from env.NODE_AUTH_TOKEN'
+  scope:
+    description: 'Optional scope for authenticating against scoped registries'
 runs:
   using: 'node12'
   main: 'lib/setup-node.js'