Improve error handling when acquiring aad tokens (#1746)

* Mostly working - some cosmetic changes remaining.

* Cosmetic changes and other tidy ups.

* More clean up.

* Move msal back to dependencies. Fix typo.

* msal should be prod dependency

* Revert msal package update as it is causing issues with unit test
execution.

* Add tracing for unhandled exceptions when acquiring tokens.

.vscode/settings.json

@@ -20,8 +20,8 @@
   "typescript.tsdk": "node_modules/typescript/lib",
   "editor.formatOnSave": true,
   "editor.codeActionsOnSave": {
-    "source.fixAll.eslint": true,
-    "source.organizeImports": true
+    "source.fixAll.eslint": "explicit",
+    "source.organizeImports": "explicit"
   },
   "typescript.preferences.importModuleSpecifier": "non-relative",
   "editor.defaultFormatter": "esbenp.prettier-vscode"