Add Bank support for "upgrade epochs" where all non-vote transactions will be rejected (bp #11082) (#11110)

* Add Bank support for "upgrade epochs" where all non-vote transactions will be rejected

(cherry picked from commit e5d8c4383f)

# Conflicts:
#	runtime/src/bank.rs

* Fix merge conflict

Co-authored-by: Michael Vines <mvines@gmail.com>

sdk/src/transaction.rs

@@ -68,6 +68,9 @@ pub enum TransactionError {
     /// implies that account locks are not taken for this TX, and should
     /// not be unlocked.
     SanitizeFailure,
+
+    /// Transactions are currently disabled due to cluster maintenance
+    ClusterMaintenance,
 }
 
 pub type Result<T> = result::Result<T, TransactionError>;