Add ability to format format event as Markdown in generic webhooks,
similar to Datadog integration.
Closes https://github.com/Unleash/unleash/issues/7646
Co-authored-by: Nuno Góis <github@nunogois.com>
## About the changes
Adds optional support for specifying JSON templates for datadog message
payload
### Important files
<!-- PRs can contain a lot of changes, but not all changes are equally
important. Where should a reviewer start looking to get an overview of
the changes? Are any files particularly important? -->
`frontend/src/component/integrations/IntegrationForm/IntegrationParameters/IntegrationParameter/IntegrationParameterEnableWithDropdown.tsx`
- a new component comprising of a text field and a dropdown menu
`src/lib/addons/datadog.ts` - Where the integration is taking place
## Discussion points
<!-- Anything about the PR you'd like to discuss before it gets merged?
Got any questions or doubts? -->
- Should I have implemented the new component type as a specifiable
addon parameter type in definitions? Felt a bit YAGNI/Premature
- Would like input on naming and the new component etc
## About the changes
<!-- Describe the changes introduced. What are they and why are they
being introduced? Feel free to also add screenshots or steps to view the
changes if they're visual. -->
<!-- Does it close an issue? Multiple? -->
Closes #
<!-- (For internal contributors): Does it relate to an issue on public
roadmap? -->
<!--
Relates to [roadmap](https://github.com/orgs/Unleash/projects/10) item:
#
-->
### Important files
<!-- PRs can contain a lot of changes, but not all changes are equally
important. Where should a reviewer start looking to get an overview of
the changes? Are any files particularly important? -->
## Discussion points
<!-- Anything about the PR you'd like to discuss before it gets merged?
Got any questions or doubts? -->
