ColumnView: Expose preferred column width setting

## Problem

As it stands, in column view each column takes up so much space that files can hardly keep 2.5 of them in view at a relatively standard window size:
Combined with the autoscrolling, users have to constantly readjust the column size and scroll.

## Proposal

Reducing the default column width to 120 would mostly alleviate the problem, as it keeps plenty of content on screen, while also fulfilling the purpose of it being a navigation-focused mode rather than something like icon grid mode. The length of text problem (if it is even a problem) could be solved both by implementing something like #1590 and also #1601

## Prior Art