runtime: Add bench for accounts::hash_internal_state (#5157)

* runtime: Add bench for accounts::hash_internal_state

* fixup! cargo fmt

* fixup! cargo clippy

* fixup! Use a more representitive number of accounts

* fixup! More descriptive name for accounts creation helper

runtime/src/lib.rs

@@ -1,4 +1,4 @@
-mod accounts;
+pub mod accounts;
 pub mod accounts_db;
 pub mod accounts_index;
 pub mod append_vec;