Check for unused exports

[pokey]

knip looks really nice. Here's the output from a quick test run.

And here's a patch to get started adding it:

From c9b0ecd29b44e5af4e844b39053e475d5d63251d Mon Sep 17 00:00:00 2001
From: Pokey Rule <755842+pokey@users.noreply.github.com>
Date: Tue, 11 Apr 2023 14:58:45 +0100
Subject: [PATCH] Introduce `knip` unused export detector

---
 package.json | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/package.json b/package.json
index 45d8d3c3e..d30fe6f53 100644
--- a/package.json
+++ b/package.json
@@ -12,6 +12,7 @@
     "init-vscode-sandbox": "pnpm --filter=@cursorless/cursorless-vscode-core init-launch-sandbox",
     "lint:meta": "pnpm run meta-updater:base --test",
     "lint:ts": "eslint packages --ext ts,tsx",
+    "lint:unused": "knip",
     "lint": "pnpm run lint:meta && syncpack list-mismatches && pnpm run lint:ts",
     "meta-updater:base": "pnpm --filter=@cursorless/meta-updater build && meta-updater",
     "preinstall": "npx only-allow pnpm",
@@ -38,6 +39,11 @@
     "tsx": "3.12.3",
     "typescript": "^5.0.3"
   },
+  "knip": {
+    "ignore": [
+      "typedoc.js"
+    ]
+  },
   "pnpm": {
     "patchedDependencies": {
       "@docusaurus/theme-search-algolia@2.3.1": "patches/@docusaurus__theme-search-algolia@2.3.1.patch"
-- 
2.39.2

• Apply above patch
• Run pnpm add -wD knip
• Investigate --strict option