Add a trigger to add `draft` label when `pull_request.draft` is `true`

[VinayakHegde]

Description:
when the PR status is changed from open to draft, there is no way to add label at this stage. We need some sort of trigger to add daft label or anything that user defined in the config.

Justification:
When the pr is is draft, it not that visible for the reviewer - there are a lot of cases where reviewer leave a lot of comments on a draft pr that probably being worked actively by the developer.

Are you willing to submit a PR?

I can try

[priyagupta108]

Hello @VinayakHegde,
Thank you for creating this feature request. We will investigate it and get back to you as soon as we have some feedback.