Add recommended vscode extensions (#53)

Author: gaprl

.vscode/extensions.json

@@ -0,0 +1,14 @@
+{
+  // See http://go.microsoft.com/fwlink/?LinkId=827846
+  // for the documentation about the extensions.json format
+  "recommendations": [
+    // TOML language support
+    "tamasfe.even-better-toml",
+    // Rust language server
+    "rust-lang.rust-analyzer",
+    // Crates.io dependency versions
+    "serayuzgur.crates",
+    // Debugger support for Rust and native
+    "vadimcn.vscode-lldb",
+  ]
+}