file_icons: Add separate icon keys for .NET solution and project files (#24851)

Add separate icon keys for .NET solution and project files.

Release Notes:

- Icon themes: Added the ability to change file icons for Visual Studio
project files:
  - Solution files (`.sln`)
  - Solution User Options files (`.suo`)
  - C# Project files (`.csproj`)
  - F# Project files (`.fsproj`)
  - Visual Basic Project files (`.vbproj`)

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/theme/src/icon_theme.rs

@@ -69,6 +69,7 @@ const FILE_ICONS: &[(&str, &str)] = &[
     ("cpp", "icons/file_icons/cpp.svg"),
     ("crystal", "icons/file_icons/file.svg"),
     ("csharp", "icons/file_icons/file.svg"),
+    ("csproj", "icons/file_icons/file.svg"),
     ("css", "icons/file_icons/css.svg"),
     ("cue", "icons/file_icons/file.svg"),
     ("dart", "icons/file_icons/dart.svg"),
@@ -82,6 +83,7 @@ const FILE_ICONS: &[(&str, &str)] = &[
     ("eslint", "icons/file_icons/eslint.svg"),
     ("font", "icons/file_icons/font.svg"),
     ("fsharp", "icons/file_icons/fsharp.svg"),
+    ("fsproj", "icons/file_icons/file.svg"),
     ("gitlab", "icons/file_icons/settings.svg"),
     ("gleam", "icons/file_icons/gleam.svg"),
     ("go", "icons/file_icons/go.svg"),
@@ -130,8 +132,11 @@ const FILE_ICONS: &[(&str, &str)] = &[
     ("toml", "icons/file_icons/toml.svg"),
     ("typescript", "icons/file_icons/typescript.svg"),
     ("v", "icons/file_icons/v.svg"),
+    ("vbproj", "icons/file_icons/file.svg"),
     ("vcs", "icons/file_icons/git.svg"),
     ("video", "icons/file_icons/video.svg"),
+    ("vs_sln", "icons/file_icons/file.svg"),
+    ("vs_suo", "icons/file_icons/file.svg"),
     ("vue", "icons/file_icons/vue.svg"),
     ("zig", "icons/file_icons/zig.svg"),
 ];