feat: add external-auth cli (#10052)

* feat: add `external-auth` cli

* Add subcommands

* Improve descriptions

* Add external-auth subcommand

* Fix docs

* Fix gen

* Fix comment

* Fix golden file

docs/cli/external-auth.md

@@ -0,0 +1,23 @@
+<!-- DO NOT EDIT | GENERATED CONTENT -->
+
+# external-auth
+
+Manage external authentication
+
+## Usage
+
+```console
+coder external-auth
+```
+
+## Description
+
+```console
+Authenticate with external services inside of a workspace.
+```
+
+## Subcommands
+
+| Name                                                         | Purpose                             |
+| ------------------------------------------------------------ | ----------------------------------- |
+| [<code>access-token</code>](./external-auth_access-token.md) | Print auth for an external provider |

docs/cli/external-auth_access-token.md

@@ -0,0 +1,39 @@
+<!-- DO NOT EDIT | GENERATED CONTENT -->
+
+# external-auth access-token
+
+Print auth for an external provider
+
+## Usage
+
+```console
+coder external-auth access-token [flags] <provider>
+```
+
+## Description
+
+```console
+Print an access-token for an external auth provider. The access-token will be validated and sent to stdout with exit code 0. If a valid access-token cannot be obtained, the URL to authenticate will be sent to stdout with exit code 1
+  - Ensure that the user is authenticated with GitHub before cloning.:
+
+     $ #!/usr/bin/env sh
+
+OUTPUT=$(coder external-auth access-token github)
+if [ $? -eq 0 ]; then
+  echo "Authenticated with GitHub"
+else
+  echo "Please authenticate with GitHub:"
+  echo $OUTPUT
+fi
+
+```
+
+## Options
+
+### --s
+
+|      |                   |
+| ---- | ----------------- |
+| Type | <code>bool</code> |
+
+Do not print the URL or access token.