Migrate to lua

configs/nvim/lua/plugins/lspconfig/rust.lua

@@ -0,0 +1,15 @@
+local function init()
+    require'lspconfig'.rls.setup {
+        settings = {
+            rust = {
+                unstable_features = true,
+                build_on_save = false,
+                all_features = true,
+            },
+        },
+    }
+end
+
+return {
+    init = init
+}