token-2022: Refactor `StateWithExtensionsMut` functionality into trait (#6329)

* Refactor `StateWithExtensionsMut` functionality into trait

* Dedupe unpack function

* Simplify passing function

program/tests/functional.rs

@@ -22,7 +22,10 @@ use {
         state::ExtraAccountMetaList,
     },
     spl_token_2022::{
-        extension::{transfer_hook::TransferHookAccount, ExtensionType, StateWithExtensionsMut},
+        extension::{
+            transfer_hook::TransferHookAccount, BaseStateWithExtensionsMut, ExtensionType,
+            StateWithExtensionsMut,
+        },
         state::{Account, AccountState, Mint},
     },
     spl_transfer_hook_interface::{