Check-in lmTools API to avoid build breaks (#12872)

Author: benmcmorran

Diff for: Extension/.gitignore

@@ -35,3 +35,7 @@ src/nativeStrings.ts
 
 vscode*.d.ts
 .scripts/_*
+
+# The lmTools API is still changing frequently. We want to avoid spontaneous
+# build breaks just because the upstream API changed in VS Code Insiders.
+!vscode.proposed.lmTools.d.ts

Diff for: Extension/package.json

@@ -6512,7 +6512,7 @@
         "translations-generate": "set NODE_OPTIONS=--no-experimental-fetch && gulp translations-generate",
         "translations-import": "gulp translations-import",
         "import-edge-strings": "ts-node -T ./.scripts/import_edge_strings.ts",
-        "prep:dts": "yarn verify dts --quiet || (npx vscode-dts dev && npx vscode-dts main)",
+        "prep:dts": "yarn verify dts --quiet || (npx vscode-dts dev && npx vscode-dts main && git checkout -- vscode.proposed.lmTools.d.ts)",
         "build": "yarn prep:dts && echo [Building TypeScript code] && tsc --build tsconfig.json"
     },
     "devDependencies": {