[Feature Request] More standard visual style for collapse

[Grumph]

Is your feature request related to a problem? Please describe.
I find it hard to read collapsed paths with | as a separator.

Describe the solution you'd like
I would like my collapse visual style be like dired-collapse or any path in a shell: long/path/to/file.txt instead of long|path|to|file.txt/.

At least I should be able to customize the | character.
(replace-string "|" "/") in dirvish-collapse--cache gives the expected result for separators.
Also, there should be no trailing / when the last element of the collapse list is a file.

Additional context
The "After collapsing" image of dired-collapse has the visual style I want.

[alexluigit]

Added option dirvish-collapse-separator in d4e5acb

Also, there should be no trailing / when the last element of the collapse list is a file.

I'm not able to reproduce this.