Supplement account_created_operation by creator name

In following cases creator field is not set (stores empty account name):

• when account was created by pow/pow2 operations (probably no explicit creator then)
• when account was created by claimed account - here creator account is provided by operation, but it's not set to vop.

We need to analyze impact of this change - for sure it can change processing in HAF dumper where this vop is actively used.