MastoAPI Accounts: Add fetching by nickname.

This is to make it easier for the frontends to handle domain.com/users/nickname
urls.

docs/Differences-in-MastodonAPI-Responses.md

@@ -19,3 +19,7 @@ Adding the parameter `with_muted=true` to the timeline queries will also return
 Has these additional fields under the `pleroma` object:
 
 - `local`: true if the post was made on the local instance.
+
+## Accounts
+
+- `/api/v1/accounts/:id`: The `id` parameter can also be the `nickname` of the user. This only works in this endpoint, not the deeper nested ones for following etc.

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

@@ -131,8 +131,8 @@ def verify_credentials(%{assigns: %{user: user}} = conn, _) do
     json(conn, account)
   end
 
-  def user(%{assigns: %{user: for_user}} = conn, %{"id" => id}) do
+  def user(%{assigns: %{user: for_user}} = conn, %{"id" => nickname_or_id}) do
-    with %User{} = user <- Repo.get(User, id),
+    with %User{} = user <- User.get_cached_by_nickname_or_id(nickname_or_id),
          true <- User.auth_active?(user) || user.id == for_user.id || User.superuser?(for_user) do
       account = AccountView.render("account.json", %{user: user, for: for_user})
       json(conn, account)

test/web/mastodon_api/mastodon_api_controller_test.exs

@@ -1064,6 +1064,17 @@ test "account fetching", %{conn: conn} do
     assert %{"error" => "Can't find user"} = json_response(conn, 404)
   end
 
+  test "account fetching also works nickname", %{conn: conn} do
+    user = insert(:user)
+
+    conn =
+      conn
+      |> get("/api/v1/accounts/#{user.nickname}")
+
+    assert %{"id" => id} = json_response(conn, 200)
+    assert id == user.id
+  end
+
   test "media upload", %{conn: conn} do
     file = %Plug.Upload{
       content_type: "image/jpg",
@@ -1950,7 +1961,7 @@ test "submit a report with statuses and comment", %{
                |> json_response(200)
     end
 
-    test "accound_id is required", %{
+    test "account_id is required", %{
       conn: conn,
       reporter: reporter,
       activity: activity