Have default media browser view tied to media source setting instead of global

[SnowCreative]

Feature request

Summary

Having a single modx_browser_default_viewmode setting in system settings isn't flexible enough.

Why is it needed?

Media sources for images and documents, for example, need two different views. Images are good using thumbnails (grid view). For documents, that's useless, and the list view is much better.

Also, modx_browser_default_sort could also be added to media sources.

Suggested solution(s)

Add a modx_browser_default_viewmode setting to each media source, and possibly modx_browser_default_sort, instead of just being global system settings.