feat: filter users by github user id in the users list CLI command (#17029)

Add the `--github-user-id` option to `coder users list`, which makes the
command only return users with a matching GitHub user id. This will
enable https://github.com/coder/start-workspace-action to find a Coder
user that corresponds to a GitHub user requesting to start a workspace.

cli/userlist.go

@@ -19,6 +19,7 @@ func (r *RootCmd) userList() *serpent.Command {
 		cliui.JSONFormat(),
 	)
 	client := new(codersdk.Client)
+	var githubUserID int64
 
 	cmd := &serpent.Command{
 		Use:     "list",
@@ -27,8 +28,23 @@ func (r *RootCmd) userList() *serpent.Command {
 			serpent.RequireNArgs(0),
 			r.InitClient(client),
 		),
+		Options: serpent.OptionSet{
+			{
+				Name:        "github-user-id",
+				Description: "Filter users by their GitHub user ID.",
+				Default:     "",
+				Flag:        "github-user-id",
+				Required:    false,
+				Value:       serpent.Int64Of(&githubUserID),
+			},
+		},
 		Handler: func(inv *serpent.Invocation) error {
-			res, err := client.Users(inv.Context(), codersdk.UsersRequest{})
+			req := codersdk.UsersRequest{}
+			if githubUserID != 0 {
+				req.Search = fmt.Sprintf("github_com_user_id:%d", githubUserID)
+			}
+
+			res, err := client.Users(inv.Context(), req)
 			if err != nil {
 				return err
 			}