[Enhancement] Use cookies on a per-source basis (#354)

* Added 'use_cookies' column to source

* Added cookies to the source form

* Updated every command to optionally include cookies

* LOTS of tests

* Made YT cookies off by default

priv/repo/migrations/20240814154844_add_use_cookies_to_sources.exs

@@ -0,0 +1,9 @@
+defmodule Pinchflat.Repo.Migrations.AddUseCookiesToSources do
+  use Ecto.Migration
+
+  def change do
+    alter table(:sources) do
+      add :use_cookies, :boolean, default: true, null: false
+    end
+  end
+end