Redo indexing mechanism (#16)

* Bumped up the line length because I fear no man

* Refactored indexing

Previously, indexing worked by collecting the video IDs of only videos
that matched indexing criteria. This new model instead stores ALL videos
for a given source, but will only _download_ videos that meet that criteria.
This lets us backfill without indexing, makes it easier to add in other
backends, lets us download one-off videos for a source that don't quite
meet criteria, you name it.

* Updated media finders to respect format filters; Added credo file

lib/pinchflat_web/controllers/media_sources/source_html/index.html.heex

@@ -29,16 +29,10 @@
           </.link>
         </:col>
         <:col :let={source} label="" class="flex place-content-evenly">
-          <.link
-            navigate={~p"/sources/#{source.id}"}
-            class="hover:text-secondary duration-200 ease-in-out mx-0.5"
-          >
+          <.link navigate={~p"/sources/#{source.id}"} class="hover:text-secondary duration-200 ease-in-out mx-0.5">
             <.icon name="hero-eye" />
           </.link>
-          <.link
-            navigate={~p"/sources/#{source.id}/edit"}
-            class="hover:text-secondary duration-200 ease-in-out mx-0.5"
-          >
+          <.link navigate={~p"/sources/#{source.id}/edit"} class="hover:text-secondary duration-200 ease-in-out mx-0.5">
             <.icon name="hero-pencil-square" />
           </.link>
         </:col>