[Enhancement] Adds ability to enable/disable sources (#481)

* [Unrelated] updated module name for existing liveview module

* Updated toggle component and moved MP index table to a liveview

* [WIP] reverted MP index table; added source count to MP index

* Moved new live table to sources index

* Added 'enabled' boolean to sources

* Got 'enabled' logic working re: downloading pending media

* Updated sources context to do the right thing when a source is updated

* Docs and tests

* Updated slow indexing to maintain its old schedule if re-enabled

* Hooked up the enabled toggle to the sources page

* [Unrelated] added direct links to various tabs on the sources table

* More tests

* Removed unneeded guard in

* Removed outdated comment

test/support/fixtures/sources_fixtures.ex

@@ -20,6 +20,7 @@ defmodule Pinchflat.SourcesFixtures do
         Enum.into(
           attrs,
           %{
+            enabled: true,
             collection_name: "Source ##{:rand.uniform(1_000_000)}",
             collection_id: Base.encode16(:crypto.hash(:md5, "#{:rand.uniform(1_000_000)}")),
             collection_type: "channel",