[e2e] Create helper function to open test-dapp transaction in dialog

**What is this about?**

See https://github.com/MetaMask/metamask-extension/pull/24352#discussion_r1593711106

Create a helper function to open various confirmations using the test-dapp.

I believe pedro just implemented one. todo: link the similar helper method here

**Stakeholder review needed before the work gets merged**

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)