merge of: Add system weights to Statemint (#762) (#918)

* Add system weights to Statemint (#762)

* waiting for weights from bm

* frame_system weights added

* cargo toml fix + fmt

* removed non-existent set_changes_trie_config

Co-authored-by: Ignacio Palacios <ignacio.palacios.santos@gmail.com>

scripts/benchmarks.sh

@@ -21,6 +21,7 @@ pallets=(
 	pallet_timestamp
 	pallet_utility
     pallet_uniques
+    frame_system
 )
 
 for p in ${pallets[@]}