* Add the entity the role was requested on into the message
* Add context and personalise role request emails

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>

This somewhat improves readability.

- it's not up to this piece of code to determine if
  emails should be sent to the used.
- that is currently done by the NotificationService itself.

Remove hardcoded sendmail "test"

This seems to have originally been factored out as part of 229a0e8
and has been sitting around since then.

Fixes GOCDB#168 (emails "from GOCDB" should come from gocdb-admins@mailman.egi.eu).

Co-Authored-By: ineilson <ian.neilson@stfc.ac.uk>

- this way, if a site role request gets passed up to an NGI level
  user, they will see the site name in the request (not the NGI
  name).

- I guess this logic was somewhat there to test /stop recursion
  if you didn't want to send an email.
- The logic of whether to send an email or just print what would
  have been sent has been factored out already, so we don't need
  this if statement anymore.

- to support different views of GOCDB being served by the same instance.

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>

- the behaviour of recursing this function is repeated further
  down.

- `if ( empty( $array_name ) )` is more readable. I think we
  previously got away with it because `[] == null` returns true,
  or because the code interchanged empty arrays and `null`.

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>

- for later reuse.

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>

- for clarity, as the email could be someone outside their entity.
- i.e, a Site role request email going to someone with a role
  over an NGI.

- this check is part of the `else` of an
  `if (count($authorisingUserIds) == 0)` statement.
- `array_unique` won't empty `$authorisingUserIds`.
- hence, the check here isn't needed.

Co-authored-by: ineilson <ian.neilson@stfc.ac.uk>