[Enhancement] Consider using pools for the various image requests to YouTube

[syeopite]

Is your enhancement request related to a problem? Please describe.

Invidious makes a lot of requests to YouTube to fetch images such as thumbnails, storyboards, etc. We should consider creating pools for these requests in order to reuse the connection and improve performance

Describe the solution you'd like

Describe alternatives you've considered

Additional context

This is mentioned a few times throughout the code. Such as:

invidious/src/invidious/routes/images.cr

Lines 56 to 59 in d956b18

	# This can likely be optimized into a (small) pool sometime in the future.
	HTTP::Client.get("https://yt3.ggpht.com#{url}") do |resp|
	return request_proc.call(resp)
	end

invidious/src/invidious/routes/images.cr

Lines 121 to 124 in d956b18

	# This can likely be optimized into a (small) pool sometime in the future.
	HTTP::Client.get("https://#{authority}.ytimg.com#{url}") do |resp|
	return request_proc.call(resp)
	end