test: Removes @vscode/test-electron

We were not using this test infrastructure, and after #56 it should be better to accomplish these tests using something like playwright.

@vscode/test-electron is really not ideal. It's heavy, and does not provide any tooling to test webviews, which we make use of.

Signed-off-by: Tyler Smalley <tyler@tailscale.com>

Author: tylersmalley

.github/workflows/test.yml

@@ -26,6 +26,8 @@ jobs:
           key: yarn-cache
       - name: Install dependencies
         run: tool/yarn install --frozen-lockfile --prefer-offline
+      - name: Test
+        run: tool/yarn test
       - name: Lint
         run: tool/yarn lint
       - name: Typescript