Add --method option to phx.routes (phoenixframework#5525)

Update the list of valid options in `Mix.Tasks.Phx.Routes`, adding a new
`--method` option, which, when combined with the `--info` option, allows
developers to specify what HTTP method should be used in conjunction
with the specified URL.
This should help in cases where the same URL matches multiple controller
actions, depending on the HTTP method. For example, an application with
a URL such as `/api/v1/users` might use it to list users, with the `GET`
method, or to create a new user, with the `POST` method.

lib/mix/tasks/phx.routes.ex

@@ -34,6 +34,7 @@ defmodule Mix.Tasks.Phx.Routes do
   ## Options
 
     * `--info` - locate the controller function definition called by the given url
+    * `--method` - what HTTP method to use with the given url, only works when used with `--info` and defaults to `get`
 
   ## Examples
 
@@ -51,6 +52,13 @@ defmodule Mix.Tasks.Phx.Routes do
         Module: RouteInfoTestWeb.PageController
         Function: :index
         /home/my_app/controllers/page_controller.ex:4
+
+  Print information about the controller function called by a specified url and HTTP method:
+
+      $ mix phx.routes --info http://0.0.0.0:4000/users --method post
+        Module: RouteInfoTestWeb.UserController
+        Function: :create
+        /home/my_app/controllers/user_controller.ex:24
   """
 
   @doc false
@@ -78,10 +86,11 @@ defmodule Mix.Tasks.Phx.Routes do
     end
   end
 
-  def get_url_info(url, {router_mod, _opts}) do
+  def get_url_info(url, {router_mod, opts}) do
     %{path: path} = URI.parse(url)
 
-    meta = Phoenix.Router.route_info(router_mod, "GET", path, "")
+    method = opts |> Keyword.get(:method, "get") |> String.upcase()
+    meta = Phoenix.Router.route_info(router_mod, method, path, "")
     %{plug: plug, plug_opts: plug_opts} = meta
 
     {module, func_name} =