Add Ruby file icon (#6922)

This icon is designed based on [Ruby's official logo], to harmonize with
the other icons.
It is deformed and simplified to be human-recognizable, even at letter
size.

[Ruby's official logo]: https://www.ruby-lang.org/en/about/logo/

Release Notes:

- Added Ruby file icon.

assets/icons/file_icons/file_types.json

@@ -79,7 +79,7 @@
         "ps1": "terminal",
         "psd": "image",
         "py": "python",
-        "rb": "code",
+        "rb": "ruby",
         "rkt": "code",
         "rs": "rust",
         "rtf": "document",
@@ -161,6 +161,9 @@
         "python": {
             "icon": "icons/file_icons/python.svg"
         },
+        "ruby": {
+            "icon": "icons/file_icons/ruby.svg"
+        },
         "rust": {
             "icon": "icons/file_icons/rust.svg"
         },

assets/icons/file_icons/ruby.svg

@@ -0,0 +1,7 @@
+<svg width="14" height="14" viewBox="0 0 14 14" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M5 7.9 4.8 12C6.1 12 8.5 10.5 9.5 9.5Z" fill="black" fill-opacity="0.6"/>
+<path d="M12 4.8 7.9 5 9.5 9.5 12 12Z" fill="black" fill-opacity="0.6"/>
+<path d="M12 4.8V12H4.8" stroke="black" stroke-width="1.25" stroke-linecap="round" stroke-linejoin="round"/>
+<path d="M2.3 7.2 2 10C2 11.8 3.6 12 4.8 12 6.5 12 8.5 10.5 9.5 9.5 10.5 8.5 12 6.5 12 4.8 12 3.6 11.8 2 10 2L7.2 2.3" stroke="black" stroke-width="1.25" stroke-linecap="round" stroke-linejoin="round"/>
+<ellipse rx="1.9" ry="3.8" cx="7.5" cy="0" transform="rotate(45)" stroke="black" stroke-width="1.25"/>
+</svg>