Fix saved-views-client tests (#56)

@itwin/saved-views-client tests were failing in release pipeline because
I didn't update tests to account for the changes in client
implementation.

Upon a closer inspection of the saved-views-client test file, I found
that
* tests weren't executing expectation verification code paths, which
made them basically inert
* `fetch` global function was not being restored after the tests were
done running
* one test was duplicated

I rewrote `ITwinSavedViewsClient.test.ts` while utilising as much of the
existing code as possible to fix these issues. I also made
saved-view-client tests run in CI pipelines and updated vitest
dependency for good measure.

.github/workflows/CI.yaml

@@ -41,5 +41,8 @@ jobs:
     - name: Typecheck
       run: npm run typecheck
 
+    - name: Check saved-views-client unit test coverage
+      run: npm run test:cover --prefix ./packages/saved-views-client
+
     - name: Check saved-views-react unit test coverage
       run: npm run test:cover --prefix ./packages/saved-views-react

packages/saved-views-client/package.json

@@ -35,6 +35,6 @@
     "happy-dom": "^10.5.2",
     "typescript": "^5.3.3",
     "vite": "^5.0.13",
-    "vitest": "^1.0.4"
+    "vitest": "^1.4.0"
   }
 }