Send webhook for deleted reports

[bgoareguer]

Description

Before this PR, trivy-operator only sent webhooks for created/updated reports.
In this PR trivy-operator also sends webhooks for deleted reports.

To make sure the receiver of the webhook can distinguish between created/updated reports and deleted reports, the webhook has been modified so that it now contains 2 fields:

• verb (can be "update" or "delete")
• report (the actual trivy-operator report)

Related issues

• Close Send a webhook when a report is deleted #1058

Checklist

• I've read the guidelines for contributing to this repository.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[chen-keinan]

@bgoareguer thanks you for the contribution , I have added few comments , also maybe it should configurable as this change might break the default integration with postee alerts and postee template , which use rego --> input.report

[chen-keinan]

@bgoareguer thank you for the PR update , I have added couple of suggestion and nit comment

[chen-keinan]

@bgoareguer look good 🚀 thank you for the contribution, last thing , do you mind updating the helm readme with new param

[chen-keinan]

lgtm 🚀