Specify default scope in verify_credentials

Certain Mastodon/Pleroma front ends call verify_credentials to get the
default scope of a new toot.

Currently, Pleroma hardcodes this value to "public".

This patch changes it to the user's default_scope value.

test/web/mastodon_api/mastodon_api_controller_test.exs

@@ -206,7 +206,19 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIControllerTest do
       |> assign(:user, user)
       |> get("/api/v1/accounts/verify_credentials")
 
-    assert %{"id" => id} = json_response(conn, 200)
+    assert %{"id" => id, "source" => %{"privacy" => "public"}} = json_response(conn, 200)
+    assert id == to_string(user.id)
+  end
+
+  test "verify_credentials default scope unlisted", %{conn: conn} do
+    user = insert(:user, %{info: %{"default_scope" => "unlisted"}})
+
+    conn =
+      conn
+      |> assign(:user, user)
+      |> get("/api/v1/accounts/verify_credentials")
+
+    assert %{"id" => id, "source" => %{"privacy" => "unlisted"}} = json_response(conn, 200)
     assert id == to_string(user.id)
   end
 
@@ -715,6 +727,18 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIControllerTest do
       assert User.following?(other_user, user) == true
     end
 
+    test "verify_credentials", %{conn: conn} do
+      user = insert(:user, %{info: %{"default_scope" => "private"}})
+
+      conn =
+        conn
+        |> assign(:user, user)
+        |> get("/api/v1/accounts/verify_credentials")
+
+      assert %{"id" => id, "source" => %{"privacy" => "private"}} = json_response(conn, 200)
+      assert id == to_string(user.id)
+    end
+
     test "/api/v1/follow_requests/:id/reject works" do
       user = insert(:user, %{info: %{"locked" => true}})
       other_user = insert(:user)