Multiple search fixes

* Remove percent-encoding of the search query when calling youtube API, as it
  breaks UTF-8
* Empty search redirects to /search, not /
* Show the fullscreen search "home page" (from #1977) at /search
* Allow 'region=' parameter to be passed to /search
* Other minor fixes

src/invidious/views/search_homepage.ecr

@@ -1,7 +1,7 @@
 <% content_for "header" do %>
 <meta name="description" content="<%= translate(locale, "An alternative front-end to YouTube") %>">
 <title>
-    Invidious
+    Invidious - <%= translate(locale, "search") %>
 </title>
 <link rel="stylesheet" href="/css/empty.css?v=<%= ASSET_COMMIT %>">
 <% end %>