E2E Test for Submit Testimony Flow

## Problem
The "Submit Testimony" flow is arguably the key feature of MAPLE, but we don't have solid tests in place around it. This makes it difficult to deploy changes due to a lack of confidence in our automatic verification.

To that end, we should add an E2E Test that covers the Submit Testimony flow to ensure the key site functionality remains functional across deploys.

## Success Criteria
* E2E Playwright Test that covers all parts of the attached test plan

## Test Plan

* Navigate to a Bill (that our test user has not submitted testimony for)
* Click Create Testimony to open the create testimony flow
* Choose any stance and click next
* Confirm that the user's legislators (set in the user profile) are auto-populate into the email recipients
* Confirm that the "Copy Email Recipients" button copies the email recipients
* Enter any text for the testimony and click next
* Confirm that the "Copy Email Body" button copies text that include the testimony text
* Click Publish and Send and Confirm that it opens the user's email client with the appropriate information (recipients + testimony in the body)
* This will be the same link on the "Send Email" button in the post-publish step, can check there as well
*Click "Finished! Back to Bill" to return to the bill page
* Confirm that the new testimony appears in the sidebar of the bill page