Add consts for all webhook actions

[puerco]

This PR defines constants for all the event webhook action types sent by GitLab.

It also reuses EventActionCreate and EventActionUpdate to define the custom CommentEventType values already defined in the module.

[puerco]

I noticed that comments have their own custom action type:

go-gitlab/event_webhook_types.go

Lines 272 to 274 in b5e0812

	Description string `json:"description"`
	Action CommentEventAction `json:"action"`
	URL string `json:"url"`

but the rest of the payload types have their action typed as string:

go-gitlab/event_webhook_types.go

Lines 1050 to 1052 in b5e0812

	URL string `json:"url"`
	Action string `json:"action"`
	Assets struct {

so I didn't add any more specific ones.

This is not modifying any of them, only defining them

[svanharmelen]

Besides the two (minor) comments, what is the end goal with this? Just defining them without using them doesn't have much use, so are you going to add move commits to this PR to also use these?

[svanharmelen]

I prefer to not tie these together and revert this change.

[puerco]

OK done 👍

[svanharmelen]

Stuff (types and consts) in this file is alphabetically ordered, so can you move these to the ordered location?

[puerco]

Moved 👍

[puerco]

My main goal as a user is to expose the values of the action from the library to applications. I didn't want to modify the payload types in event_webhook_types.go to use them not to break compatibility but I can if you are fine with it! It would certainly be better.

[svanharmelen]

Yeah while it might cause a few issues, I think it's the best what to actually guarantee the list will stay up-to-date over time. So I would say go ahead and update the EventType fields to use this new const.