Allows users to add details about a bugreport in progress.

The "bugreport in progress" notification now have a "DETAILS" button
that when clicked opens a dialog window displaying the following fields:

  - Name: short name for the bugreport, will be used as part of the
    final files (and by default is the timestamp sent by dumpstate)
  - Title: a 1-line title for the bugreport, will be used as the subject
    in the final message.
  - Description: a detailed description for the bug.

The main advantage of such dialog is that it allows users to enter more
info about a bugreport while it's being generated, rather then when the
bugreport is finished (since of the user doesn't remember what the
context was when the problem happened).

BUG: 25794470
BUG: 10676443
Change-Id: I0d1dba2a94ad989e541415a2a59475619a2e3d13