Add minor convenience features to search

src/invidious.cr

@@ -443,7 +443,7 @@ get "/search" do |env|
 
   operators = query.split(" ").select { |a| a.match(/\w+:[\w,]+/) }
   operators.each do |operator|
-    key, value = operator.split(":")
+    key, value = operator.downcase.split(":")
 
     case key
     when "channel", "user"

src/invidious/search.cr

@@ -169,7 +169,7 @@ def produce_search_params(sort : String = "relevance", date : String = "", conte
               "\x30\x01"
             when "3d"
               "\x38\x01"
-            when "live"
+            when "live", "livestream"
               "\x40\x01"
             when "purchased"
               "\x48\x01"