Add file icon for Ballerina (.bal) files (#56799)

## Summary

- Adds a `ballerina` icon key to the default icon theme, mapping the
`.bal` file suffix to a new SVG under
`assets/icons/file_icons/ballerina.svg`.
- Icon is the monochrome Ballerina mark from the official WSO2 VS Code
extension, rescaled to Zed's 16×16 viewBox.

## Icon source / license

The SVG is adapted from `ballerina-inverse.svg` in
[wso2/vscode-extensions](https://github.com/wso2/vscode-extensions),
which is Apache-2.0 licensed. The original 400×400 geometry is preserved
via the existing `translate`/`scale` transform; only the viewBox and
fill were normalized to match the convention used by the other icons in
`assets/icons/file_icons/`.

## Test plan

- [x] `cargo build --release --bin zed`
- [x] Opened a folder containing `.bal` files and confirmed the icon
renders in the project panel and tabs.
- [x] Alphabetical ordering preserved in both
`FILE_SUFFIXES_BY_ICON_KEY` and `FILE_ICONS`.

Release Notes:

- N/A

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>
Co-authored-by: Danilo Leal <67129314+danilo-leal@users.noreply.github.com>

assets/icons/file_icons/ballerina.svg

@@ -0,0 +1,8 @@
+<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M4.57391 3.54203V5.2877L5.96882 5.81793C6.73561 6.10752 7.38411 6.35224 7.41674 6.36039C7.46161 6.37263 7.46977 5.96476 7.46977 4.08858V1.80044H6.02184H4.57391V3.54203Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+<path d="M8.53021 4.08451C8.53021 5.34074 8.54245 6.36856 8.56284 6.36856C8.57916 6.36856 9.22359 6.12384 9.99853 5.8261L11.4057 5.28771L11.4179 3.54205L11.4261 1.80046H9.97814H8.53021V4.08451Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+<path d="M4.57391 7.1435C4.57391 7.54728 4.58615 7.87766 4.60654 7.87766C4.66772 7.87766 6.49089 7.16797 6.49089 7.1435C6.49089 7.11902 4.66772 6.40934 4.60654 6.40934C4.58615 6.40934 4.57391 6.73971 4.57391 7.1435Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+<path d="M10.4186 6.76826C9.91696 6.95996 9.50909 7.12718 9.50909 7.1435C9.50909 7.16797 11.3323 7.87766 11.3975 7.87766C11.4138 7.87766 11.4261 7.54728 11.4261 7.1435C11.4261 6.58064 11.4138 6.40934 11.3771 6.41341C11.3486 6.41749 10.9162 6.57656 10.4186 6.76826Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+<path d="M5.9729 8.46498L4.57391 8.99929V11.5974V14.1996H5.32439C6.00553 14.1996 6.07894 14.1914 6.09933 14.1262C6.11157 14.0895 6.42563 13.0616 6.79679 11.8421L7.46977 9.63148V8.77496C7.46977 8.11422 7.45753 7.91844 7.42082 7.92252C7.39227 7.9266 6.73969 8.16724 5.9729 8.46498Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+<path d="M8.53021 8.77904V9.63964L9.1828 11.785C9.5458 12.9678 9.85986 13.9957 9.88025 14.065L9.92512 14.1996H10.6756H11.4261L11.4179 11.5974L11.4057 8.99929L9.99853 8.45682C9.22359 8.16316 8.57916 7.91844 8.56284 7.91844C8.54245 7.91844 8.53021 8.30591 8.53021 8.77904Z" fill="#C6CAD0" stroke="#C6CAD0" stroke-width="0.483833"/>
+</svg>

crates/theme/src/icon_theme.rs

@@ -80,6 +80,7 @@ const FILE_SUFFIXES_BY_ICON_KEY: &[(&str, &[&str])] = &[
         ],
     ),
     ("backup", &["bak"]),
+    ("ballerina", &["bal"]),
     ("bicep", &["bicep"]),
     ("bun", &["lockb"]),
     ("c", &["c", "h"]),
@@ -312,6 +313,7 @@ const FILE_SUFFIXES_BY_ICON_KEY: &[(&str, &[&str])] = &[
 const FILE_ICONS: &[(&str, &str)] = &[
     ("astro", "icons/file_icons/astro.svg"),
     ("audio", "icons/file_icons/audio.svg"),
+    ("ballerina", "icons/file_icons/ballerina.svg"),
     ("bicep", "icons/file_icons/file.svg"),
     ("bun", "icons/file_icons/bun.svg"),
     ("c", "icons/file_icons/c.svg"),