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/edit.html.heex

@@ -8,11 +8,7 @@
 <div class="rounded-sm border border-stroke bg-white px-5 pb-2.5 pt-6 shadow-default dark:border-strokedark dark:bg-boxdark sm:px-7.5 xl:pb-1">
   <div class="max-w-full overflow-x-auto">
     <div class="flex flex-col gap-10">
-      <.source_form
-        changeset={@changeset}
-        media_profiles={@media_profiles}
-        action={~p"/sources/#{@source}"}
-      />
+      <.source_form changeset={@changeset} media_profiles={@media_profiles} action={~p"/sources/#{@source}"} />
     </div>
   </div>
 </div>