Rename media sources (#25)

* Renamed MediaSource to Sources

* Renamed MediaItem controller namespace

lib/pinchflat_web/controllers/sources/source_html/new.html.heex

@@ -0,0 +1,14 @@
+<div class="mb-6 flex gap-3 flex-row items-center">
+  <.link :if={!Plug.Conn.get_session(@conn, :onboarding)} navigate={~p"/sources"}>
+    <.icon name="hero-arrow-left" class="w-10 h-10 hover:dark:text-white" />
+  </.link>
+  <h2 class="text-title-md2 font-bold text-black dark:text-white ml-4">New Source</h2>
+</div>
+
+<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"} />
+    </div>
+  </div>
+</div>