Support .ion-files in Peek

[Korb]

Description of the new feature / enhancement

First of all, a quick look at descript.ion files.

Scenario when this would be used?

View a commented list of the contents of the current folder.

Supporting information

I couldn't find an official specification for this format. You can read more about the syntax here. However, there is no need for syntax highlighting or interactivity - just plain-text viewing, as is currently the case when using Peek to open .txt files.

[crutkas]

this should be easy if it is just a txt file rendering. #32817 shows how to do this.