Rename rust-icon.png to just icon.png

Author: Xanewok

rust-icon.png renamed to icon.png

@@ -4,7 +4,7 @@
     "description": "Rust for Visual Studio Code (powered by Rust Language Server/Rust Analyzer). Provides lints, code completion and navigation, formatting and more.",
     "version": "0.7.8",
     "publisher": "rust-lang",
-    "icon": "rust-icon.png",
+    "icon": "icon.png",
     "galleryBanner": {
         "color": "#336356",
         "theme": "dark"