Extend endpoint to fix out of Sync RevReg with Askar by updating locally held accumulator

[swcurran]

Recently, an endpoint was added to "fix" an out of sync RevReg. Out of sync in this case can be caused by an Issuer trying to revoke a credential, but the update on the ledger failing, leaving the two out of sync. To address this, an ACA-Py endpoint was added that recalculated the accumulator from the list of revoked credentials, and updates the ledger. However, this still does not prevent future revocation errors because the agent retains a copy of the accumulator that is not updated. Using the Indy SDK this value cannot be updated, as outlined in issue #1868.

Update the endpoint (added in PR #1783) when Askar is being used to the save the accumulator in Askar storage so that future updates occur properly, and match what is on the ledger.