The "Modified" header moves sort caret icon to next line if sidebar is narrow

[krassowski]

Description

Reproduce

1. Sort by modified
2. Resize the sidebar in 4.2.0b3

Expected behavior

Context

• JupyterLab version: 4.2.0b3

[krassowski]

With #16207:

There are two options:

• have a third state, the earlier proposed "Mod." for the most narrow option (and delete the ... "too narrow" indicator logic)
• change the "too narrow" indicator logic to kick in eariler

CC @JasonWeill

[krassowski]

This also looks bad when there is an extra column.

I think we need a more generic logic on minimum width of each column and to allow each column to change size separately.