Add text/uri-list support for `paste_img`

When copying images from Nautilus or Thunar, these programs actually copy to the clipboard in the form of `text/uri-list`. `ObsidianPasteImg` only searches for `image/png` data within the clipboard using `wl-paste --list`. This update adds support to inspect the list, extract the first image, and add it to `wl-clipboard` as an image. Ultimately, you can copy from file browser to neovim.