[vscode] Update workspace file to better respect local style

This change updates lk.code-workspace to specify
* editor.detectIndentation as false, as otherwise that overrides
  the desired editor.tabSize setting.
* editor.insertSpaces as true, since spaces are preferred over tabs.
* editor.formatOnSave as false for C and C++ files, as - in the absence
  of a .clang-format file - the clangd extension is likely to default to
  choices that don't respect the local style.

lk.code-workspace

@@ -5,6 +5,19 @@
         }
     ],
     "settings": {
+        // Disable auto-formatting till the project decides on a
+        // machine-readable config to control it (e.g., .clang-format).
+        "[c]": {
+            "editor.formatOnSave": false,
+        },
+        "[cpp]": {
+            "editor.formatOnSave": false,
+        },
+        // Allows editor.tabSize to be specified (otherwise it is overridden as
+        // auto-detected).
+        "editor.detectIndentation": false,
+        // Convert tabs to spaces.
+        "editor.insertSpaces": true,
         "editor.tabSize": 4,
         "files.exclude": {
             "**/.cache": true,