Add event for AccessControl._setRoleAdmin

[nventuro]

Whenever a role's admin is set by _setRoleAdmin, we should emit an event indicating this happened.

Not only is this useful to react to admin changes, it will also help in dynamic role schemes, where a role hierarchy may be set up without any account having the roles.

[Skyge]

That is good, how about the name of this new event is NewRoleAdmin or something else?

[nventuro]

We name events as verbs in the past tense, so it'd have to be something like RoleAdminChanged. I now wonder if _setRoleAdmin shouldn't be _changeRoleAdmin: 'set' might give the impression of it being a one-off thing.

[julianmrodri]

@nventuro I would like to tackle this if you are OK. Not sure whats the expected timeline but can take a look during the weekend if required. Can do just the event or also the renaming if we agree. Let me know, just looking on how to contribute :)

[nventuro]

Go for it! The event alone should be fine, it'll be a straightforward PR :)

[julianmrodri]

@nventuro Just submitted PR. Ran the tests and lintern and seems to be fine. I dont think we have to modify the CHANGELOG. Please let me know how it looks. Thanks!

[Skyge]

I now wonder if _setRoleAdmin shouldn't be _changeRoleAdmin: 'set' might give the impression of it being a one-off thing.

As far as I am concerned, the function name is OK, the 'set' also means it can 'change', of course, in order to make it more clear, we can add some comments.