Use JSON for favorites, move server list code to Lua (#10085)

Co-authored-by: sfan5 <sfan5@live.de>

doc/menu_lua_api.txt

@@ -253,32 +253,6 @@ Package - content which is downloadable from the content db, may or may not be i
         }
 
 
-Favorites
----------
-
-core.get_favorites(location) -> list of favorites (possible in async calls)
-^ location: "local" or "online"
-^ returns {
-    [1] = {
-        clients       = <number of clients/nil>,
-        clients_max   = <maximum number of clients/nil>,
-        version       = <server version/nil>,
-        password      = <true/nil>,
-        creative      = <true/nil>,
-        damage        = <true/nil>,
-        pvp           = <true/nil>,
-        description   = <server description/nil>,
-        name          = <server name/nil>,
-        address       = <address of server/nil>,
-        port          = <port>
-        clients_list  = <array of clients/nil>
-        mods          = <array of mods/nil>
-    },
-    ...
-}
-core.delete_favorite(id, location) -> success
-
-
 Logging
 -------