feature request: PDF viewer

[Havunen]

I want to be able preview PDF files

[Lej77]

I experimented with building a simple PDF viewer using GPUI at https://github.com/Lej77/pdf-reader-gpui so that might be useful. For a while I had issues with memory leaks because I didn't realize you had to call Window::drop_image to free created images but otherwise it was quite straightforward.