Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

This exposes `Note`s on Issues & MergeRequests using a
`Types::Notes::NoteableType` in GraphQL.

Exposing notes on a new type can be done by implementing the
`NoteableType` interface on the type. The presented object should
be a `Noteable`.

Makes `Note#edited?` return `false` when the note body was not edited

Add support for group entities to quick actions

There is a combination of few strategies implemented here:

1. Few relations were eager loaded
2. Changed few polymorphic routes to specific ones so we don't have to
   use `#becomes(Namespace)` which doesn't preserve association cache

[master]Fixed ability to comment on and edit/delete comments on locked or confidential issues

See merge request gitlab/gitlabhq!2612