[PATCH] Paint Style Dialog Window does not update styles when closed and styles are changed in preferences

[taylor.smock]

Steps to reproduce:
1) Open JOSM
2) Create a new layer
3) Ensure that the Map Paint Styles toggle dialog is not visible (i.e., not collapsed or uncollapsed)
4) Add or remove a paint style in Preferences -> Map Settings -> Map Paint Styles
5) Click OK
6) Open the Map Paint Styles toggle dialog (Windows -> Map Paint Styles)
7) Look for the added/removed paint style

[taylor.smock]

Minimal patch

[Don-vip]

In 15612/josm:

fix #18458 - Paint Style Dialog Window does not update styles when closed and styles are changed in preferences (patch by taylor.smock)