Add an option to disable code completion

package.json

@@ -170,6 +170,11 @@
                     "type": "number",
                     "default": 0.55,
                     "description": "Opacity of inactive regions (used only if clangd.inactiveRegions.useBackgroundHighlight=false)"
+                },
+                "clangd.enableCodeCompletion": {
+                  "type": "boolean",
+                  "default": true,
+                  "description": "Enable code completion provided by the language server"
                 }
             }
         },

src/clangd-context.ts

@@ -106,6 +106,8 @@ export class ClangdContext implements vscode.Disposable {
       middleware: {
         provideCompletionItem: async (document, position, context, token,
                                       next) => {
+          if (!config.get<boolean>('enableCodeCompletion'))
+            return new vscode.CompletionList([], /*isIncomplete=*/ false);
           let list = await next(document, position, context, token);
           if (!config.get<boolean>('serverCompletionRanking'))
             return list;