Added UpdateHook method to RepositoryService.

[chhsia0]

The new UpdateHook method in RepositoryService would update an existing
SCM webhook and overwrite the list of events to watch.

In this patch, UpdateHook is not supported in the GitLab driver. It is
implemented separately in a followup patch.

[chhsia0]

@bradrydzewski if the changes to the contents of Hook.Events in the GitLab driver breaks Drone, I could instead introduce a new Hook.NativeEvents field to have the actual names of the event options in GitLab.

[bradrydzewski]

can you provide some more details regarding the breaking change?

[bradrydzewski]

I would also ask that we split this pull request into smaller chunks. For example, there is some refactoring or changes that may not be required to implement UpdateHook. Also in some cases we don't have full test coverage of things being refactored which makes me nervous that I might merge changes that cause a regression.

[bradrydzewski]

thanks for the explanations. My recommendation would be to submit the PR without GitLab support (make it a no-op, using an ErrNotImplemented) and then we handle GitLab support in a separate pull request. I think everything else is straight-for and can be merged right away, however, GitLab will take some time and would benefit from being reviewed separately (especially since it could have breaking impacts). Does that sound ok?

[bradrydzewski]

awesome, thanks so much!