Add options for retrieving/replacing **all** subplots on a layout

[kMutagene]

Description

Since the member names of subplots on a layout are dynamic, e.g. a layout can have multiple scenes, scene, scene2, scene<n>, bugs can be caused by high-level APIs that retrieve and change subplot objects, for example Chart.Grid @ #413.

Repro steps

see #413

Suggested Solution

functions on Layout and their top-level equivalents on the Chart API must provide options to retrieve and replace all instances of a subplot. The concrete solution for #413 would look like this:

chart
|> ``get all scenes on the chart``
|> ``when there is more than one scene present, choose a sensible default, e.g. the first one``
|> ``style the retrieved single scene accordingly``
|> ``set the scene on the layout, removing all scenes that are there