refactor: Customize tsconfig types declaration for utils (#3327)

This pull request makes a small update to the TypeScript configuration
for Karma tests in `packages/utils`. The change adds type definitions
for `jest` and `jest-extended` to ensure proper type support when
running tests.

## Notes

For some reason ts does not complain about the missing
`@streamr/test-utils` in the utils package. It should, really. It's not
its dependency. It will (would) in the future (when we intro bundles).

Author: mondoreale

packages/utils/tsconfig.karma.json

@@ -1,6 +1,10 @@
 {
   "extends": "../../tsconfig.karma.json",
   "compilerOptions": {
+    "types": [
+      "jest",
+      "jest-extended"
+    ],
     "outDir": "dist"
   },
   "include": [