Pruning Webhook Run Tables

[canny]

The webhook_executions and triggered_webhooks tables in the pact broker seem to grow without restriction over time, and if I've correctly understood are in the nature of audit information. It would be good to have some capability via REST and/or the pact broker CLI to remove data relating to webhook executions subject to some criteria (e.g. older than a specified date).

https://pact.canny.io/admin/board/feature-requests/p/pruning-webhook-run-tables

[canny]

This issue has been linked to a Canny post: Pruning Webhook Run Tables 🎉