Slimmer implementation of credit-only accounts (#4592)

* Add credit-only debit/data check to verify_instruction

* Store credits and pass to accounts_db

* Add InstructionErrors and tests

* Relax account locks for credit-only accounts

* Collect credit-only account credits before passing to accounts_db to store properly

* Convert System Transfer  accounts to credit-only, and fixup test

* Functionalize collect_accounts to unit test

* Review comments

* Rebase

sdk/src/instruction.rs

@@ -52,6 +52,12 @@ pub enum InstructionError {
     /// Program modified the data of an account that doesn't belong to it
     ExternalAccountDataModified,
 
+    /// Credit-only account spent lamports
+    CreditOnlyLamportSpend,
+
+    /// Credit-only account modified data
+    CreditOnlyDataModified,
+
     /// An account was referenced more than once in a single instruction
     DuplicateAccountIndex,