Add an icon for typst (.typ)

[jonsch318]

Add the typst-t icon for .typ files.

Typst A new markup-based typesetting system that is powerful and easy to learn. It can be seen as an alternative to latex.
I think it is popular enough with the Typst LSP Extension getting 45.9K downloads.

I asked for permissions from the authors, and it is a valid use of their right https://typst.app/legal/brand.

The icon looks like