This PR adds the following fields to webhooks:
- 'DisplayName' - the display name of the webhook for easier recognition in UI (no uniqueness guarantees)
- 'Description' - an (optional) description of the webhook
- 'LatestExecutionResult' - contains the result of the latest execution of the webhook
This change introduces:
- webhook type / store / controller / handler
- webhookExecution type / store / controller / handler
- foreign key fix for sqlite3