Add a way to keep a persistent connection between requests

[mackuba]

If you're making a lot of requests, it makes sense to open one HTTP connection and reuse it for many requests. In net/http, one connection is reused if you call Net::HTTP.start with a block and make multiple requests inside that block, or if you create an instance using Net::HTTP.new.

I need to think about how the API for this should look, but for now I'm locally testing something like this:

class Minisky
  attr_accessor :http_connection

  def make_request(request)
    response = @http_connection.request(request)
  end
end

api = Minisky.new('public.api.bsky.app', nil)

Net::HTTP.start('public.api.bsky.app', 443, use_ssl: true) do |http|
  api.http_connection = http

  ... api.fetch_all ...
end