[Enhancement] Added ability to detect when files have been deleted (#399)

* Added function for updating a media item's filepaths on-disk

* Added placeholder action to source page

* Turned the file sync into a job and properly hooked it up to the controller

lib/pinchflat/media/file_syncing_worker.ex

@@ -0,0 +1,38 @@
+defmodule Pinchflat.Media.FileSyncingWorker do
+  @moduledoc false
+
+  use Oban.Worker,
+    queue: :local_data,
+    tags: ["sources", "local_data"]
+
+  alias __MODULE__
+  alias Pinchflat.Repo
+  alias Pinchflat.Tasks
+  alias Pinchflat.Sources
+  alias Pinchflat.Media.FileSyncing
+
+  @doc """
+  Starts the source file syncing worker.
+
+  Returns {:ok, %Task{}} | {:error, %Ecto.Changeset{}}
+  """
+  def kickoff_with_task(source, opts \\ []) do
+    %{id: source.id}
+    |> FileSyncingWorker.new(opts)
+    |> Tasks.create_job_with_task(source)
+  end
+
+  @doc """
+  Deletes a profile and optionally deletes its files
+
+  Returns :ok
+  """
+  @impl Oban.Worker
+  def perform(%Oban.Job{args: %{"id" => source_id}}) do
+    source = Repo.preload(Sources.get_source!(source_id), :media_items)
+
+    FileSyncing.sync_file_presence_on_disk(source.media_items)
+
+    :ok
+  end
+end