Retry failed requests reported via AcaPy Webhook calls

[PaulWen]

Currently, we receive many errors via AcaPy Webhook calls. Maybe, just retrying them would allow us to still process them and therefore make the system more reliable and resiliant.

[PaulWen]

In order to retry a connection issuance after an error has been reported via the webhooks, would require the controller to store a list of all pending credential issuances to be able to tricker them again in case of a failiure.