Add icon for R files (#8223)

Add an icon from https://www.svgrepo.com/svg/340612/logo-r-script for .r

<img width="1392" alt="307467014-63f68791-9d74-4bd1-8065-3698665f7c15"
src="https://github.com/zed-industries/zed/assets/93369643/ce24615c-6946-479a-8660-663bf83a7dde">

Credits For Image: @moshyfawn

Release Notes:

- Added R logo

assets/icons/file_icons/file_types.json

@@ -118,6 +118,7 @@
         "rebar.config": "erlang",
         "rkt": "code",
         "rs": "rust",
+        "r": "r",
         "rtf": "document",
         "sav": "storage",
         "scm": "code",
@@ -246,6 +247,9 @@
         "rust": {
             "icon": "icons/file_icons/rust.svg"
         },
+        "r": {
+            "icon": "icons/file_icons/r.svg"
+        },
         "settings": {
             "icon": "icons/file_icons/settings.svg"
         },

assets/icons/file_icons/r.svg

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="15px" height="14px" viewBox="0 0 15 14" version="1.1">
+<g id="surface1">
+<path style=" stroke:none;fill-rule:evenodd;fill:rgb(0%,0%,0%);fill-opacity:1;" d="M 14.0625 6.46875 C 14.0625 4.203125 11.125 2.367188 7.5 2.367188 C 3.875 2.367188 0.9375 4.203125 0.9375 6.46875 C 0.9375 8.488281 3.273438 10.160156 6.34375 10.503906 L 6.34375 11.8125 L 8.582031 11.8125 L 8.582031 10.511719 C 9.113281 10.457031 9.636719 10.359375 10.148438 10.21875 L 11.058594 11.8125 L 13.589844 11.8125 L 12.0625 9.410156 C 13.292969 8.667969 14.0625 7.625 14.0625 6.46875 Z M 3.515625 6.773438 C 3.515625 5.226562 5.75 3.96875 8.503906 3.96875 C 11.257812 3.96875 13.292969 4.828125 13.292969 6.773438 C 13.304688 7.757812 12.671875 8.644531 11.699219 9.015625 C 11.65625 8.988281 11.609375 8.964844 11.558594 8.941406 C 11.355469 8.851562 11.144531 8.78125 10.933594 8.71875 C 10.933594 8.71875 12.886719 8.582031 12.886719 6.765625 C 12.886719 4.949219 10.839844 4.914062 10.839844 4.914062 L 6.34375 4.914062 L 6.34375 9.300781 C 4.671875 8.847656 3.515625 7.886719 3.515625 6.773438 Z M 9.957031 7.582031 L 8.601562 7.582031 L 8.601562 6.410156 L 9.957031 6.410156 C 10.125 6.398438 10.292969 6.453125 10.410156 6.5625 C 10.53125 6.675781 10.597656 6.828125 10.585938 6.984375 C 10.589844 7.144531 10.527344 7.296875 10.410156 7.410156 C 10.289062 7.519531 10.128906 7.582031 9.957031 7.582031 Z M 8.582031 9.109375 L 9.183594 9.109375 C 9.300781 9.113281 9.40625 9.15625 9.484375 9.238281 C 9.578125 9.320312 9.65625 9.414062 9.722656 9.511719 C 9.34375 9.554688 8.964844 9.574219 8.582031 9.578125 Z M 8.582031 9.109375 "/>
+</g>
+</svg>