Various fixes for new mapping properties in form, change client_max_body_size...

Various fixes for new mapping properties in form, change client_max_body_size value for futurproofness and add properties tests

plugins/netbox-rps-plugin/netbox_rps_plugin/api/serializers.py

@@ -123,6 +123,10 @@ class MappingSerializer(NetBoxModelSerializer):
             "proxy_cache",
             "proxy_read_timeout",
             "client_max_body_size",
+            "proxy_send_timeout",
+            "proxy_max_temp_file_size",
+            "proxy_buffering",
+            "proxy_request_buffering",
             "extra_protocols",
             "sorry_page",
             "custom_fields",