feat: Add option for pre and post request hooks

[abborg]

Add options for pre- and post-request hooks to allow users to execute some behavior before and/or after a webhook request is made. This is to allow for observability around the requests being made as well as other actions that require information about the webhook being fired, the payload, and the response.

[danihodovic]

Hello mr Abborg. Can you list a few example use cases for this pull-request?

[abborg]

My intended use case for these hooks is to allow for emitting metrics or traces from before and after the webhook fires. The hooks could also be used to allow for adding specific headers or manipulating the payload - for example to sanitize fields being sent for PII or other sensitive data.

[danihodovic]

For serialization #35 is related.

For metrics / traces I use Prometheus and https://github.com/danihodovic/celery-exporter to track success / failure of webhook events

[abborg]

I think your celery-exporter might solve my use case nicely. I'll take a look and follow up. Thanks!

[danihodovic]

I think your celery-exporter might solve my use case nicely. I'll take a look and follow up. Thanks!

Once you plug in Prometheus, use the generated Grafana dashboards to see aggregated task metrics.