Add initial RubyLLM and Provider Rerank implementation

Author: infinityrobot

lib/ruby_llm.rb

@@ -46,6 +46,10 @@ def embed(...)
       Embedding.embed(...)
     end
 
+    def rerank(...)
+      Rerank.rank(...)
+    end
+
     def paint(...)
       Image.paint(...)
     end

lib/ruby_llm/provider.rb

@@ -43,6 +43,12 @@ def paint(prompt, model:, size:, connection:)
         parse_image_response(response, model:)
       end
 
+      def rank(query, documents, model:, connection:, top_n:, max_tokens_per_doc:) # rubocop:disable Metrics/ParameterLists
+        payload = render_rerank_payload(query, documents, model:, top_n:, max_tokens_per_doc:)
+        response = connection.post(rerank_url(model:), payload)
+        parse_rerank_response(response, model:)
+      end
+
       def configured?(config = nil)
         config ||= RubyLLM.config
         missing_configs(config).empty?