Slack webhook support

### Contact Details [Optional]

_No response_

### Feature Description

Extend webhook providers collection with support for Slack.

### Problem or Use Case

_No response_

### Proposed Solution

_No response_

### Alternatives Considered

_No response_

### Additional Context

_No response_

### Priority

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### Code of Conduct

- [x] I agree to follow this project's Code of Conduct