Add VSCode Rust Analyzer Settings

Fixes errors reported by rust analyzer due to differing target and a
missing cargo feature.

.vscode/settings.json

@@ -1,4 +1,10 @@
 {
   "editor.formatOnSave": true,
-  "editor.rulers": [100]
+  "editor.rulers": [100],
+  "rust-analyzer.cargo.target": "aarch64-unknown-none-softfloat",
+  "rust-analyzer.cargo.features": ["bsp_rpi3"],
+  "rust-analyzer.checkOnSave.allTargets": false,
+  "rust-analyzer.checkOnSave.extraArgs": ["--lib", "--bins"],
+  "rust-analyzer.lens.debug": false,
+  "rust-analyzer.lens.run": false
 }