Create E2E tests for expected right-click actions

Mocha tests can't cover the [`contributes.menus` section](https://github.com/confluentinc/vscode/blob/06be4f664ea41f9a27a80d69dfe4f0b970c4832b/package.json#L1187) of package.json and what actions we expect to be available on elements loaded into our contributed views.

We _could_ assert the strings within package.json, but that won't cover the various context values we set for different connections' resources.