Proxy: Use connection pools for images (#4326)

Theoretically this should improve memory usage and performance by quite a bit
as we aren't creating a new HTTP::Client and in a turn a new connection for
every image we request from YouTube.

Closes issue 4009

src/invidious.cr

@@ -93,6 +93,10 @@ SOFTWARE = {
 
 YT_POOL = YoutubeConnectionPool.new(YT_URL, capacity: CONFIG.pool_size)
 
+# Image request pool
+
+GGPHT_POOL = YoutubeConnectionPool.new(URI.parse("https://yt3.ggpht.com"), capacity: CONFIG.pool_size)
+
 # CLI
 Kemal.config.extra_options do |parser|
   parser.banner = "Usage: invidious [arguments]"